text: Updated | Older fathers appear to have geekier sons, scientists have discovered. In a study of over 30,000 twins, researchers found boys who had older fathers scored higher on the “geek index”—and that the older the father, the higher the score. (The geek effect was only seen in boys.) 
   
   By the age of 12, boys with older fathers were found to be more intelligent, more focused on their interests and were less concerned about whether or not they fitted in with their peers. 
   
   While there has been much research showing the negative impact having children later in life can have—including increased risk of autism and schizophrenia—little has been done into the potential benefits. 
   
   The latest study, published in the journal Translational Psychiatry on Tuesday, indicates there are evolutionary advantages for men having children later in life. 
   
   Scientists from the U.K and the U.S. collected cognitive and behavioral data on 15,000 sets of twins. At the age of 12, they completed tests measuring their “geeky” traits, including their non-verbal IQ, their focus on subjects of interest and their social aloofness. Parents were asked how they were perceived by their peers and if they had interests that dominated their time. 
   
   From this, the researchers were able to produce a “geek index score” for each child in the study and to compare it to the age of the parents. 
   
   Their findings showed a correlation between the age of the father and the geekiness of the sons, with a positive correlation between the two—the older the father, the geekier the son. They also noticed geek traits appeared more after the age of 45. 
   
   Geeky boys did better in school exams, especially STEM (Science, Technology, Engineering and Maths) subjects, suggesting they would be more successful in their careers as adults. 
   
   The authors say there are several limitations to the study. They were not able to determine whether the geek effect extended beyond secondary education and future success, adding it “remains possible that personality traits associated with GI [geek index] cease to be advantageous in later life.” For example, being flexible and socially aware rather than focusing on a single goal may provide more benefits in the work environment in the long-term. 
   
   They also said they could not verify whether geek traits were associated with things like poor emotional and social functioning. 
   
   However, they said the findings show there may be some benefits associated with having an older father. 
   
   Study author Magdalena Janecka tells Newsweek: “Our primary hypothesis is that higher levels of those ‘geeky’ traits in offspring of older men are mainly due is due to characteristics of the fathers themselves. Men who decide to delay fatherhood often do so due to their extended career and educational pursuits, and likely themselves display higher levels of ‘geekiness.’” 
   
   Another implication of the study is the link between autism and higher paternal age. The scientists were not able to measure the link directly, but say that some of the genes relating to geekiness and autism overlap, and that these genes may be more prevalent in older fathers. 
   
   If a child is only born with some of these genes, it may help them succeed in school, but if they get a “higher dose,” they may be more at risk of autism. 
   
   This link could also explain why the geek effect was only seen in boys. “We think the reasons for this may be similar to those why females seem protected from autism in general,” Janecka says. “For some reason, there could be a selective passage of those traits from fathers to son, but biologically, we still do not know how this could work.” 
   
   She also says girls with older fathers may well be geeky too, just in different ways: “Another possibility is that we have not measured ‘geekiness’ in a way that allows to capture its manifestation in females—there remains a caveat that daughters of older men are just as geeky, but we could not capture it in the current study.” 
   
   The study, Janecka adds, does not mean men should put off having children until they are older in the hope of having more intelligent sons. “Those findings should definitely not be taken to guide individual decisions about parenthood,” she says. “Effects we are describing are visible in large samples, but may operate very differently in cases of individual families.” 
   
   Patrik Magnusson, from the Karolinska Institutet in Sweden, has studied the link between parental age and autism risk. Commenting on the study, he tells Newsweek: “That geekiness is associated with school success is not strange at all, to be a geek is defined as being someone with skills that are very well suited for school. That geekiness is associated with having an old father is a little stranger.” 
   
   He says this link is likely down to several different factors, including geekiness being heritable. Another could be that men who get the chance to become fathers at a later age need to show “special positive skills.” 
   
   “This special skill may be genetic and transmitted to the offspring,” he says. “Also, fathers that wait with kids may predominantly be fathers that have spent time studying or spent time developing ideas or business in favour of a the more common family life. Such personality is likely genetically inherited.” 
   
   This story has been updated to include comments from Patrik Magnusson. ||||| Older men tend to have “geekier” sons who are more aloof, have higher IQs and a more intense focus on their interests than those born to younger fathers, researchers claim. 
   
   The finding, which emerged from a study of nearly 8,000 British twins, suggests that having an older father may benefit children and boost their performance in technical subjects at secondary school. 
   
   
   
   Researchers in the UK and the US analysed questionnaires from 7,781 British twins and scored them according to their non-verbal IQ at 12 years old, as well as parental reports on how focused and socially aloof they were. The scientists then combined these scores into an overall “geek index”. 
   
   
   
   Magdalena Janecka at King’s College London said the project came about after she and her colleagues had brainstormed what traits and skills helped people to succeed in the modern age. “If you look at who does well in life right now, it’s geeks,” she said. 
   
   
   
   Drawing on the twins’ records, the scientists found that children born to older fathers tended to score slightly higher on the geek index. For a father aged 25 or younger, the average score of the children was 39.6. That figure rose to 41 in children with fathers aged 35 to 44, and to 47 for those with fathers aged over 50. 
   
   
   
   The effect was strongest in boys, where the geek index rose by about 1.5 points for every extra five years of paternal age. The age of the children’s mothers seemed to have almost no effect on the geek index. 
   
   
   
   When the scientists looked at the children’s achievements at school they found that having a high IQ, a tendency to focus intensely and social aloofness were all linked to children taking more technical GCSEs. When children displayed all three traits, the effect was even more pronounced, the researchers write in the journal Translational Psychiatry. Overall, children who were born when their fathers were 50 or older were 32% more likely to achieve two A or A* grades at GCSE than children born to men aged under 25. 
   
   Janecka said the study is one of the first to suggest that having an older father can have benefits for a child. Previous work by Janecka and others has found that children born to older men are more at risk of medical conditions including autism and schizophrenia. 
   
   
   
   The scientists calculate that 57% of the geek index score is inherited, but that figure is likely to vary with age. If right, it suggests that DNA and the environment have roughly an equal share in how geeky someone turns out. Writing in the journal, the researchers speculate that there may be some overlap with genes that contribute to autism and a high score on their index. 
   
   
   
   The effect that a father’s age had on their child’s geek index remained when the researchers took into account the men’s qualifications, their job and socioeconomic status. “We have known for a while about the negative consequences of advanced paternal age, but now we have shown that these children may also go on to have better educational and career prospects,” Janecka said. She added that some of the genes that contribute to geekiness and academic success might also lead to a higher risk of autism when a child inherits more of them. “With a higher ‘dose’ of these genes, and when there are other contributing risk factors, they may end up with a higher predisposition to autism.” 
   
   The findings do not, however, make an unshakeable argument for delaying fatherhood. Bill Gates and Mark Zuckerberg rank among the greatest geeks in the world but both of their fathers were about 30 when they had their sons. 
   
   If the findings are right, it is unclear why the effect is much stronger for boys than girls. Janecka said that the study may simply have failed to capture how girls display geekiness. “Maybe we aren’t measuring geekiness properly. They may be geeky in a different way to boys,” she said. But it is also possible that whatever averts autism in girls – five times as many males are diagnosed than females – also shields them from the most geeky traits. 
   
   Research is under way to recognise why older parents are more likely to have children with particular mental disorders. One theory pinpoints mutations that build up in parents’ sperm and eggs. But with geekiness, the answer could lie in geekier men simply being more likely to delay fatherhood. 
   
   “Certain men who delay fatherhood tend to be better educated and have better jobs and a higher geek index and they pass those genetics nto their offspring,” said Janecka. “It causes them to delay fatherhood, but other factors might contribute too.” ||||| Citation: Translational Psychiatry (2017) 7, e1156; doi:10.1038/tp.2017.125 
   
   Published online 20 June 2017 
   
   M Janecka1,2, F Rijsdijk1, D Rai3, A Modabbernia2 and A Reichenberg2,4 
   
   Advanced paternal age (APA) at conception has been associated with negative outcomes in offspring, raising concerns about increasing age at fatherhood. Evidence from evolutionary and psychological research, however, suggests possible link between APA and a phenotypic advantage. We defined such advantage as educational success, which is positively associated with future socioeconomic status. We hypothesised that high IQ, strong focus on the subject of interest and little concern about ‘fitting in’ will be associated with such success. Although these traits are continuously distributed in the population, they cluster together in so-called ‘geeks’. We used these measures to compute a ‘geek index’ (GI), and showed it to be strongly predictive of future academic attainment, beyond the independent contribution of the individual traits. GI was associated with paternal age in male offspring only, and mediated the positive effects of APA on education outcomes, in a similar sexually dimorphic manner. The association between paternal age and GI was partly mediated by genetic factors not correlated with age at fatherhood, suggesting contribution of de novo factors to the ‘geeky’ phenotype. Our study sheds new light on the multifaceted nature of the APA effects and explores the intricate links between APA, autism and talent. 
   
   Top of page Introduction Advanced paternal age (APA) at conception has been associated with a number of adverse neuropsychiatric outcomes in offspring, particularly autism spectrum disorders1, 2 and schizophrenia.3, 4 Although well replicated, it is plausible that these observations reflect only one side of the nature of the APA effects. Given that historically, conceiving a child later in life was indicative of biological fitness,5 there could also exist a link between APA and a phenotypic advantage. In an environment characterised by high mortality, only the fittest males would survive and be able to reproduce when old,6 passing their advantageous traits onto offspring. Alternatively, more recent indices of ‘fitness’—including extended educational and career pursuits—could themselves correlate with an older age at fatherhood. Either of these selection mechanisms could help offset negative effects of de novo genetic mutations that accumulate in paternal sperm with age.7 Despite broad evidence concerning negative consequences of early parenthood, the potential advantage of APA has received very little attention. Very young parents tend to be characterised by lower education and economic disadvantage,8 and their offspring were shown to be at increased risk for educational underachievement, crime, substance abuse and health problems.9 Although the effects of early reproduction are likely qualitatively different from those of APA,10 it may seem surprising that the possibility of protective effects of delayed parenthood has thus far received so little attention. Here we investigated whether having an older father is associated with certain beneficial traits. We defined such advantageous phenotype based on considerations of what could be ‘adaptive’ in the modern environment. We hypothesised that high IQ; ability to retain strong focus on the subject of interest; and some degree of social aloofness are likely to be particularly beneficial in the knowledge-driven economy. Although these traits are continuously distributed in the population, ethnographic literature groups them under an umbrella-term ‘geek’ (‘intelligent outcast’; ‘labelled because of their expertise and lack of social skills’; ‘socially awkward and overly intellectual (…) prone to obsessive interests’11, 12, 13). Therefore, we labelled our composite measure of non-verbal intelligence, restrictive interests and reduced need to fit in with the peer group as ‘geek index’ (GI). We validated our measure of GI by verifying its scope to predict future academic achievement. Although the GI components were all independently associated with school results, we show they are most beneficial when co-occurring in the ‘geek’ cluster. Finally, we tested the hypothesis that advancing paternal age is associated with higher GI in offspring. Using data from the Twin Early Development Study (TEDS), a British, population-representative study of twins, allowed us to further examine sex differences, as well as genetic and environmental contributions to this index. 
   
   Top of page Materials and methods Sample The study used the TEDS sample, a large nationally representative cohort of British twins.14 There were 12 468 twins from 6234 families assessed at the age of 12, with data on relevant questionnaires available for 8601 (4528 families; questionnaire details below). Out of these, 7781 (4097 families) individuals had complete data on all covariates. This subset of individuals had higher mean maternal and paternal ages than those recorded in the full sample (<1 year difference for both), lower CAST scores (6% difference), higher Raven’s Matrices test results (1% difference) and higher academic achievement at age 16 (4% difference; Supplementary Table S1). All sample descriptives are presented in Supplementary Table S1. Measures GI was computed using child’s scores of (i) non-verbal intelligence, (ii) restrictive and repetitive behaviours (RRBs) and (iii) social aloofness. Scores on the Raven’s Standard Progressive Matrices15 test were used to obtain (i). Childhood Autism Spectrum Test16 (CAST) scores were used to obtain both (ii) and (iii). CAST measures came from parental reports (see Supplementary Table S2 for the list of items), and the cognitive tests were completed by the TEDS participants via web platforms; all assessments took place at the age of 12. Covariates in the adjusted models included socioeconomic status (SES; index of parent qualifications and employment, and mother’s age at birth of first child), maternal age at conception, sex and zygosity. Education achievement was measured using the results of nationally standardised exams taken in the United Kingdom typically at the age of 16 in a wide range of subjects (General Certificate of Secondary Education, GCSE). The curriculum and awarding of GCSEs is overseen by examination boards regulated by the British government, ensuring consistent standards across the country and throughout the time. All pupils are required to sit exams in English Language and Literature, Mathematics and Science, but are otherwise free to choose among a number of other subjects. Science, technology, engineering and mathematics (STEM) subjects refer to the part of the school curriculum that focuses on development of the knowledge and skills essential for a number of science and technology-related careers. As such, they have been the focus of the educational policies in both United Kingdom and United States.17, 18, 19 High attainment in the STEM subjects have been consistently shown to predict future income over and above overall school performance, with STEM degree majors earning on average more than $15 000 per year than non-STEM degree majors in full-time jobs.20, 21 Geek index GI scores were computed by multiplying the non-verbal cognitive scores with the sum of the CAST social and RRBs items (after weighing down high RRB scores—see below). In order to avoid the confusion between GI and autism symptoms, and to ensure that our construct represents an advantageous trait, we recoded very high RRB scores (Supplementary Table S3), so that the highest GI scores were associated with midrange RRB values. In addition, all scales contributing to GI were linearly transformed, so that 1 represented a true score of 0, 2 a score of 1 and so on. This was done to avoid obtaining GI=0 for all individuals scoring 0 on at least one of the GI subscales, as a result of multiplication by 0. Finally, to ensure that our results did not arise due to unequal contribution of measures used to compute GI, or transformation of the RRB score described above, all analyses were also done using (i) standardised subscales and (ii) non-transformed RRB scores. Statistical analysis All analyses were conducted using R22 (version 3.2.2) and OpenMX.23 Validation of the GI To establish whether GI can predict future academic attainment, we looked at the association between GI and school results at the age of 16. The measure of academic performance reflected a product of grade score and qualification value, in approximate number of GCSE equivalents (A levels completed at this age were assumed to be double the workload of GCSEs). This enabled us to obtain an index of school attainment for all individuals regardless of the qualification taken. Given the evidence that attainment in STEM subjects is a stronger predictor of future income than attainment in Art subjects, we also investigated the association between GI and (i) number of STEM GCSEs taken, (ii) mean grades at STEM GCSEs and (iii) probability of obtaining A or A* in at least two STEM GCSEs. The effect of GI on academic performance was tested using linear and logistic mixed models fitted by maximum-likelihood procedure, with a random effect of family ID around the intercept (lme4 package), and controlling for the effects of SES, sex, zygosity and maternal age. We also verified whether the cognitive and behavioural traits used to derive the GI were associated with choosing more STEM GCSEs when clustering together, rather than existing independently of each other. We defined high/low levels of the GI subscales as ±1 s.d. from the mean, and looked at mean number of STEM GCSEs in ‘geeks’ (high IQ, socially aloof, high RRBs), compared to individuals with (i) high IQ, not socially aloof and low RRBs score and (ii) low IQ, socially aloof and high RRBs score. To investigate how specific this effect was, we performed similar analyses for GCSEs in Art subjects. Finally, we used structural equation modelling (lavaan package) to verify whether a latent construct underlain by RRBs score, non-verbal IQ and social aloofness are associated with school results at age 16. Association between paternal age and GI The association between paternal age (treated as a continuous variable) and GI was investigated using mixed models, in line with the procedures described above. Both linear and quadratic models were investigated, and a log-likelihood ratio test was used to evaluate whether adding quadratic component significantly improved the fit of the model. To validate that the association between paternal age and GI is stronger than that between paternal age and the GI subscales, we compared the size and significance level of paternal age effects on the standardised GI subscales. Given the evidence for the sexually dimorphic nature of the paternal age effects,1, 24 we tested whether the link between GI and paternal age differs between males and females. Furthermore, to ensure that our results did not arise due to either very limited number of offspring of fathers in the highest paternal age categories (paternal age >51) or enrichment of autism cases among the offspring of older men, all analyses were also conducted in (i) a subset of children with fathers aged 50 or younger at conception, and (ii) after excluding individuals with a confirmed autism diagnosis. Mediation between paternal age and education outcomes We tested the association between association paternal age and conception, applying mixed models methodology, as specified above. Next, we investigated whether this association is mediated by the effects of paternal age on GI. In line with the other procedures, this was done using a multilevel framework (mediation package), thus controlling for the family structure in our data. Paternal age was specified as a predictor, GI as a mediator and exam results as the outcome, with the covariates including SES, maternal age, zygosity and—where appropriate—sex. For each model, we run 100 simulation and used a bootstrap procedure to estimate 95% Quasi–Bayesian confidence intervals of the effect size estimates. Testing our hypothesis of sexually dimorphic effects of APA, we run the mediation analysis separately for male and female offspring. Effects of paternal age on heritability of GI We derived tetrachoric correlations for GI in mono- (MZ) and dizygotic (DZ) twins in OpenMx, using raw data full information maximum-likelihood estimation. Given the high MZ correlation (which was more than twice the DZ correlations and suggestive of dominance effects), we ran both ADE and AE univariate twin models to obtain the standardised genetic and environmental variance components for the trait. For more details on these models see Rijsdijk and Sham,25 and Neale and Maes.26 Subsequently, we ran a basic GxE model27 on GI with paternal age as moderator. This allowed us to partition the genetic and environmental effects on GI into those that are moderated and those that are independent of paternal age. As the moderating effects on the variance components in this model could be biased by a (genetic) correlation between moderator and GI, paternal age effects were regressed out of the GI scores prior to fitting the GxE model. This model allowed us to get an insight into the mechanisms behind the association between paternal age and GI—due to perfect correlation of paternal age in MZ and DZ twins, it would not be possible to formally test the genetic and environmental contributions to this association otherwise. 
   
   Top of page Discussion In summary, male offspring of older fathers had higher ‘geek index’ scores, a composite measure of high IQ, strong focus on the subject of interest and social aloofness. To our knowledge, this is the first time that APA was shown to associate with an advantageous outcome. GI was positively linked with future academic attainment—including the key predictors of future SES—suggesting a phenotypic advantage in the offspring of older fathers. Using a population-based longitudinal twin sample protects against bias and enhances generalisability, while controlling for the key covariates—including maternal age, SES and sex—and adjusting for the family structure mitigates against inflation in the reported effects. Molecular underpinnings of the effects of APA on GI Our study offered new insights into the molecular mechanisms underlying the APA effects on offspring. We showed that GI was 57% heritable, highlighting the importance of the genetic factors in educational success.29 Both familial, additive genetic effects and de novo mutations—including those accumulating in paternal sperm with age—likely contributed to this measure of heritability. We acknowledge that ‘geekiness’ likely runs in families, and correlates with paternal age at conception—and therefore, the association observed in our study is underlain largely by familial factors. Nevertheless, our results suggest that genetic influences on GI may extend beyond those. First, all associations between paternal age an GI in males remained significant after controlling for SES, which—indexing parental education and employment status—likely correlates with parental GI. Second, using a GxE model we showed that the genetic, but not environmental, contribution to GI variance increases with paternal age. In other words, genes were becoming more important in determining the GI as paternal age increased. Controlling for the genetic correlation between GI and paternal age limited the chance that the observed association arose solely due to the genetic make-up of men who decide to delay fatherhood, therefore suggesting potential contribution of de novo genetic factors. Such multifactorial nature of the APA effects—with relatively minor contribution of de novo effects—is in line with the results from recent population genetics model,30 and represents a consensus between multiple lines of evidence from molecular and epidemiological research.7, 31, 32, 33 Although these studies focused largely on the mechanisms of association between APA and neurodevelopmental disorders, as we explain below, they can provide useful insights in unravelling the factors underlying the link between paternal age and GI. ‘Geekiness’, autism and talent It is possible that the factors mediating the association between advanced paternal age and GI are overlapping with those between advanced paternal age and autism.1, 32, 34, 35 Although autism is a complex neurodevelopmental disorder that is qualitatively different from being a ‘geek’, it is possible that some of its facets are captured by the index measured in the current study. Indeed, original descriptions of autistic disorders by Kanner (1943) and Asperger (1944) involved a notion that the associated personality characteristics are relevant for development of high-level skills (‘astounding vocabulary of the speaking children, the excellent memory for events of several years before, the phenomenal rote memory for poems and names, and the precise recollection of complex patterns and sequences, bespeak good intelligence’ (Kanner, 194336); ‘the problems are compensated by a high level of original thought and experience. This can often lead to exception achievements later in life’ (Asperger, 1944, translated by Uta Frith37). Several studies point towards high prevalence of individuals with the broad autism phenotype in certain professional groups, including academics, engineers and musicians.38, 39, 40, 41, 42 Furthermore, superior performance on non-verbal cognitive tasks in individuals on the autism spectrum versus controls has been shown before,43 and common genetic variants for autism were predictive of higher IQ in the general population.44 We showed that GI was positively associated with educational attainment, including the measures particularly predictive of future SES, and fully mediated the positive association between paternal age and school results. Although we could mitigate against the results being biased by the inclusion of individuals with a diagnosis of autism, it is likely that the effects of APA on autism symptomatology in offspring are continuously distributed in the general population,2, 45 contributing to the patterns reported in the current study. If advanced paternal is associated with familial and de novo molecular events that contribute to autism, it could also contribute to the ‘cognitive strengths’ associated with the liability to this disorder—and our results capture some of this signal. Of particular interest here is the recent evidence suggesting that familial risk for autism can be partitioned into several components, including a cluster of variants contributing to high IQ.46 Although our focus here remained on the beneficial effects of APA, we must emphasise they are likely to be specific to the modern knowledge-based environment, without necessarily having such advantageous effects historically. In other words, offspring of older fathers are not inherently biologically ‘fit’; rather, the cluster of behavioural and cognitive traits, which we showed they are enriched for, conveys an advantage in modern times. This is supported by a recent study investigating offspring fitness in relation to paternal age in historical and current cohorts, with a total sample size of over 1.3 million and data spanning four centuries.47 Although APA was strongly associated with increased infant mortality in pre-industrial populations, this relationship was reversed in the 20th-century Sweden, suggesting relative recency of the phenomenon of APA-related advantage. Sexual dimorphism of the effects of APA and the ‘geek index’ The notion that APA mediated geekiness and autism via partly overlapping pathways fits in with our observations of sexually dimorphic effects of APA on GI. Previous studies consistently reported higher rates of autism in males versus females,48, 49 with suggestions of a female protective factor contributing to this gender imbalance.50 Such protective effects have yet to be characterised, with mechanisms proposed to date including X chromosome-mediated effects,51 role of hormones,52, 53 differential gene expression54 and social factors.55 Nevertheless, how these mechanisms could interact with the familial and de novo genetic factors for autism/GI discussed above remains to be elucidated. The notion of sexually dimorphic effects of APA on offspring has received some attention before, however, the evidence emerging from the research to date remains inconclusive. The majority of studies reporting sex differences in the APA effects suggested higher risk for APA-related disorders in female than in male offspring, with up to three-fold increase in risk in girls compared to boys.1, 56, 57 However, neither the meta-analysis of APA-schizophrenia studies by Miller et al.,57 nor multi-cohort autism study by Sandin et al.58 confirmed the presence of such differences. Comparison with previous findings At first, our findings seem to be at odds with previous research suggesting an association between APA and lower cognitive skills. However, the results to date have been mixed, with some studies reporting lack of APA effects on IQ,59 and others a decrease in cognitive performance in the offspring of aged fathers.50, 51 In the largest study reporting effects of paternal age on educational attainment, D’Onofrio et al.34 showed that higher paternal age was associated with better school performance (D’Onofrio appendix) in population-based analyses. In our study, advanced paternal age was associated with higher scores on the Raven’s Progressive Matrices test (data not shown), therefore the lack of agreement between our findings and the literature cannot be attributed to compounding the non-verbal IQ with other measures. Discrepancies in research could be explained by different ages of the populations studied, differences in definitions of both the outcome measure and the covariates (particularly SES), and analytical methods. It is worth noting that results regarding maternal age contribution to offspring cognitive outcomes are similarly inconclusive, with literature providing the evidence for either direction of its effects.60, 61 Strengths and limitations Our novel hypothesis, analytical methods and use of a large, population-representative sample of twins, are the main strengths of our study. Controlling for SES and maternal age, we could ensure that our results did not arise solely due to higher levels of education, better financial status in men who conceive later in life or maternal factors. Furthermore, using a mixed-model approach allowed us to leverage the unique twins data set without the risk of inflating results. Finally, we verified that our findings were not driven by outliers in the sample, and remained significant after excluding individuals of very old fathers (>50 years) or those with a diagnosis of autism. The study has, however, several limitations. It was not possible to determine whether the advantageous effects of GI extend beyond secondary education, and correlate with future SES. It remains possible that personality traits associated with GI cease to be advantageous later in life. In career settings, cognitive flexibility and ability to tune in to subtle social cues may convey more benefits than strong focus and pursuing one’s goal irrespective of others’ opinion. Although we could show that GI was strongly associated with measures of educational attainment in STEM subjects, which has been previously shown to strongly predict future income, we could not test these effects directly because cohort members are young. We also could not verify whether high GI is associated with any adverse outcomes, for example, worse socioemotional functioning, and we acknowledge that the ‘geek’ phenotype has yet to be fully characterised. Finally, we could not control for paternal age at birth of his first child. Although this would be a useful predictor of the socioeconomic index composite and would help verify the GI in offspring of men who delay versus those who extend fatherhood, relevant data had not been collected. 
   
   Top of page Conclusions Results of our study indicate that APA is associated with some phenotypic advantage in male offspring. A cluster of behavioural and cognitive traits identified as characteristic of ‘geeks’ was strongly predictive of academic, and thus likely also career success. We could show that paternal age is more strongly associated with such combination of traits than any of these traits alone, suggesting a special relationship between APA and educational attainment. Such an association is likely to be mediated by factors similar to those linking APA and autism. Our results provide original insights into the possibility of phenotypic advantage associated with delayed fatherhood. 
   
   Top of page Conflict of interest The authors declare no conflict of interest. 
   
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   Top of page Acknowledgements We thank Anastasio Nougos for his insights. The authors also acknowledge funding given to Magdalena Janecka (Seaver Autism Centre Fellowship) and Abraham Reichenberg (MIEHS grant, MINERvA), as well as thank Professor Robert Plomin for granting us access to the Twin Early Development Study (TEDS) data and his helpful comments on the manuscript. We gratefully acknowledge the ongoing contribution of the participants in the TEDS and their families. TEDS is supported by a program grant to Robert Plomin from the UK Medical Research Council (MR/M021475/1 and previously G0901245). Author contributions MJ, AR, DR and AM conceived the study design; FR and MJ worked on the statistical analyses; MJ, FR, DR, AM and AR wrote the manuscript. 
   
   Supplementary Information accompanies the paper on the Translational Psychiatry website ||||| Image copyright Getty Images Image caption A stereotype of a geek, holding a cupcake 
   
   Men who delay starting a family are more likely to have "geekier" sons, a study suggests. 
   
   They were brighter, more focused and less bothered about fitting in - according to the "Geek Index" devised by King's College London. 
   
   The mother's age had no impact, and daughters seemed to be immune. 
   
   One scientist said a trend for delayed parenthood might mean we were heading towards a "society of geniuses" able to solve the world's problems. 
   
   The findings are rare good news in the science of delayed fatherhood. 
   
   Repeated studies have shown that older sperm is more prone to genetic errors and children are more likely to develop autism and schizophrenia. 
   
   The researchers looked at test results from 15,000 twins taking part in a huge study tracking their development. 
   
   The team then created the Geek Index by scoring the twins geeky traits, when they were 12, by looking at their: 
   
   non-verbal IQ 
   
   ability to focus on a subject 
   
   social aloofness 
   
   Those with a high geek score, unsurprisingly, went on to do better at school - particularly in the fields of science, technology, engineering and mathematics. 
   
   Possible explanations include: 
   
   Geekier dads could be taking longer to start a family and pass on geeky traits to their children 
   
   Older men have a home setting (due to stable, better paid jobs giving more access to education or experience from previous children) that encourages geeky traits 
   
   New mutations in sperm that affect development 
   
   Dr Magdalena Janecka, from King's College London, told the BBC News website: "Paternal age should not be the main focus when we're thinking about risk, individual families should not influence their decisions on parenthood based on these findings." 
   
   The gender differences are not fully explained. 
   
   It could be the measure of geekiness failed to spot differences in how it emerged in boys and girls, the scientists said. Or it could be down to differences in the way the brains of the boys and girls developed. 
   
   Prof Allan Pacey, from the University of Sheffield, said: "Whilst it may be chic to be a geek, I would not recommend that would-be parents delay their plans to start a family to specifically increase the odds of having a child with geek-like qualities. 
   
   "The dangers of older parenting are well described, such as an increased risk of infertility, miscarriage, or conceiving a child with a variety of debilitating disorders. 
   
   "However, I do find the idea of a 'geek gene' quite intriguing, and, given our recent trend to have our children later in life, perhaps we are destined for future society of geniuses that are going to help us solve all the world's problems." 
   
   The research team also believe some genetic traits being inherited from older fathers could be affecting both geekiness and autism. 
   
   Dr Janecka said: "When the child is born only with some of those genes, they may be more likely to succeed in school. 
   
   "However, with a higher 'dose' of these genes, and when there are other contributing risk factors, they may end up with a higher predisposition for autism." 
   
   Follow James on Twitter.
target: – A new study suggests an upside for boys who have older dads: higher IQs. More specifically, they tend to score higher on what the researchers call the "geek index," reports the Guardian. And this is clearly seen as a positive: "If you look at who does well in life right now, it’s geeks," says Magdalena Janecka at King’s College London. The geek index, she explains, is determined by such factors as ability to focus, non-verbal IQ scores taken at age 12, and social aloofness. The latter trait may sound like a negative, but the BBC frames it as the boys not being overly concerned with fitting in. A mother's age appears to have no impact. The team studied more than 7,000 sets of twins in the UK. The average geek score for boys born to dads 25 or younger is 39. It goes up to 41 when dads had the child between 35 and 44, and jumps to 47 when dads were 50 or older. The impact was less pronounced on girls, and more pronounced when measuring science, tech, engineering, and math scores. Kids born to fathers 50 or older were 32% more likely to earn at least two A's on standardized tests than children born to men aged under 25, the researchers report in Translational Psychiatry. They calculate that 57% of the geek index score is inherited, with possible overlap between genes that contribute to a high geek score and to autism. “Our primary hypothesis is that higher levels of those ‘geeky’ traits in offspring of older men are mainly due is due to characteristics of the fathers themselves," Janecka tells Newsweek. "Men who decide to delay fatherhood often do so due to their extended career and educational pursuits, and likely themselves display higher levels of ‘geekiness.’” (Younger fathers are also likelier to die younger.)