Sons and brothers of convicted sex offenders are more likely to be convicted of sex crimes than others, a recent study claimed . The implication is that the potential for committing a sex offence may be written in our genes - but while this is an interesting finding, it is unlikely to help prevent sex crimes or catch offenders. This is because the genes that make up the people who we are, and the environments in which we are raised cannot be considered independently of each other. The brothers of men convicted of sex offences are five times more likely than average to commit similar crimes, a study found. Johnny Savile (left) is accused of abusing seven women, while Jimmy Savile (right) raped and sexually assaulted patients in 41 hospitals during a 24 year reign of abuse . The research analysed DNA from 21,566 men convicted of sex offences in Sweden between 1973 and 2009. It found that sons and brothers of convicted sex offenders were four to five times more likely to be convicted of sex crimes than men in the general population. In seeking to explain this connection, the researchers found that in only 2 per cent of cases could this familial connection be explained by shared environmental factors. This can include social or environmental aspects of their upbringing that siblings would have experienced together. On the other hand, their shared genetics were a factor in 40 per cent of cases, with the remaining 58 per cent of cases stemming from environmental factors not shared between family members. Genetic factors were also found to be stronger for child molestation (46 per cent) than for adult rape (19 per cent). While the study makes an estimate of the heritability of sexual offending, it cannot of course pinpoint the genes that might be involved. Dr Mairi Levitt says that genetic material from both parents is passed on, but genetic traits are developed through interaction between genes and the environment . Putting a figure on the genetic basis for behaviour seems to suggest that these factors are inherited directly by the children from their parents. Of course genetic material from both parents is passed on, but genetic traits are developed through interaction between genes and the environment. As can be seen from the percentages above, the largest proportion of cases involved a large, rag bag of environmental factors that are by far the greatest influence on behaviour. You may not have been born a criminal, but a combination of genes and environment could control your fate when it comes to anti-social behaviour. This is according to a recent study which found that experiences, such as divorce and sexual abuse, could affect gene expressions that control a person's predisposition to delinquency. The study used a survey of 1,337 students aged 17 or 18 in Västmanland, Sweden, who anonymously completed questionnaires reporting on their behaviour. As well as their behaviour, they spoke about past family conflict, experiences of sexual abuse, and the quality of their relationship with their parents. They also provided a sample of saliva from which the researchers extracted DNA. One of the genes examined was Monoamine oxidase A (MAOA). This gene is a key enzyme which breaks down and releases energy in brain neurotransmitters, such as serotonin. The transmitter be a contributor to feelings of well-being and happiness . 'About 25 per cent of Caucasian men carry the less active variant of MAOA,' explained Professor Sheilagh Hodgins, a researcher at the University of Montreal. 'Among them, those who experience physical abuse in childhood are more likely than those who are not abused to display serious anti-social behaviour from childhood through adulthood.' Separating  nature and nurture may be useful as a model but does not really make sense because research has demonstrated that gene development is affected by the environment. Any report of genes influencing behaviour tends to polarise opinion. Some may welcome the science and see this as confirmation that sex offenders are biologically different from other people and could perhaps be prevented from offending. Others will be concerned about the stigmatisation of family members defined as 'at risk', but still unlikely to offend themselves. Only about 2.5 per cent of brothers or sons of convicted sex offenders were also convicted so the preventative programmes aimed at at-risk families would mainly target the innocent. So what then might this mean in practical terms? The discovery could perhaps one day lead to the identification of specific genotypes but could or should this affect the way we deal with sex offenders? A genotype has already been identified that increases the risk of violent behaviour in specific environments. Dubbed the 'criminal' or 'warrior' gene, it has in some cases even been used successfully by defence teams in mitigation pleas to avoid the death penalty in the US, or reduce the length of sentences in the US and Italy. It might be thought odd that a convicted murderer, who is at increased risk of offending and therefore presumably more dangerous to the public in the future, would be treated more leniently. Sex offenders, particularly where children are involved, are probably even more stigmatised than other violent criminals so perhaps a genetic defence would not work in their favour. What is clear is that finding genetic influences on behaviour does not affect legal responsibility. It is recognised that there are many genetic, biological and environmental factors that influence behaviour, and it may be harder for all sorts of reasons for some people to refrain from criminal acts than others. Any research that helps us to understand problem behaviours is to be welcomed, but the headline figure – a genetic link in 40 per cent of cases – does not tell us that sex offenders 'can't help it' or are different from 'normal' people. Dr Maria Levitt is a Senior Lecturer at Lancaster University. This article originally appeared in The Conversation .
Recent study found sons and brothers of convicted sex offenders were four to five times more likely to be convicted of sex crimes .
Some argue this knowledge could help prevent people from offending .
Dr Mairi Levitt says the genetic study can't separate nature from nurture .