Genetic studies on Turkish people

Population genetics research has illuminated the ancestry of the modern Turkish people (not to be confused with Turkic peoples) in Turkey. Studies have sought to determine the relative contributions of the Turkic peoples of Central Asia, from where the Seljuk Turks began migrating to Anatolia after the Battle of Manzikert in 1071, which led to the establishment of the Anatolian Seljuk Sultanate in the late 11th century, and prior populations in the area who were culturally assimilated during the Seljuk and the Ottoman periods.
Turkish genomic variation, along with several other Western Asian populations, looks most similar to genomic variation of South European populations such as southern Italians. Western Asian genomes, including Turkish ones, have been greatly influenced by early agricultural populations in the area; later population movements, such as those of Turkic speakers, also contributed. A whole-genome sequencing study of Turkish genetics, conducted on 16 individuals, concluded that the Turkish population forms a cluster with Southern European and Mediterranean populations and that the predicted contribution from ancestral East Asian populations (presumably reflecting a Central Asian origin) is 21.7%. However, that does not provide a direct estimate of a migration rate, because of factors such as the unknown original contributing populations. The genetic variation of various populations in Central Asia "has been poorly characterized"; Western Asian populations may also be "closely related to populations in the east". 
Multiple studies have found similarities or common ancestry between Turkish people and present-day or historic populations in the Mediterranean Basin, West Asia and the Caucasus. Other studies have found that Turkish people cluster with Southern and Mediterranean European populations along with groups in the northern part of Southwest Asia (such as the populations from Caucasus, Northern Iraq, and Iran) and have the lowest fixation index distance from Caucasus and Iranian-Syrian populations. Multiple studies have also found Central Asian contributions.
Central Asian connection.
Several studies have investigated to what extent a gene flow from Central Asia to Anatolia contributed to the gene pool of the Turkish people and the role of the 11th-century settlement by Oghuz Turks. The difficulty of distinguishing the effects of different migratory episodes complicates the effort to give reliable estimates. Thus, although the Turks' settlement of Anatolia was of cultural importance, including the introduction of the Turkish language and Islam, the genetic contribution from Central Asia may have been slight, according to some studies.
Some of the Turkic peoples originated from Central Asia may be related to the Xiongnu. Most (89%) of the Xiongnu sequences belong to Asian haplogroups, but nearly 11% belong to European haplogroups. Thus, contacts between European and Asian populations predated the Xiongnu culture, confirming results reported for two samples from an early 3rd century B.C. Scytho-Siberian population.
A study of 75 individuals from various parts of Turkey concluded that the "genetic structure of the mitochondrial DNAs in the Turkish population bears some similarities to Turkic Central Asian populations".
A 2001 study comparing the populations of Mediterranean Europe and Turkic-speaking peoples of Central Asia estimated the Central Asian genetic contribution to current Anatolian Y-chromosome loci (one binary and six short tandem repeat) and mitochondrial DNA gene pool to be roughly 30%. A 2004 high-resolution SNP analysis of Y-chromosomal DNA in samples collected from blood banks, sperm banks, and university students in eight regions of Turkey found evidence for a weak but detectable signal (<9%) of gene flow from Central Asia. A 2006 study estimated Central Asian genetic contribution to Anatolia with respect to Kyrgyzstan, Kazakhstan, Xinjiang, Turkmenistan, and Uzbekistan to be 13% for the Y chromosome, 22% for mitochondrial DNA, 15% for Alu insertions (autosomal), and 22% for microsatellites (autosomal). It was later observed that the male contribution from Central Asia to the Turkish population with reference to the Balkans was 13%. For all non-Turkic speaking populations, the Central Asian contribution was higher than in Turkey. According to the study, "the contributions ranging between 13%–58% must be considered with a caution because they harbor uncertainties about the state of pre-nomadic invasion and further local movements."
As of 2017, Central Asian genetic variation has been poorly studied, with no whole genome sequencing studies for countries such as Turkmenistan and Afghanistan. There are also no such studies for transition countries in Western Asia. Therefore, future comprehensive genome-wide studies are needed. Central Asian populations near Western Asia may also be related closely to Western Asian populations, including Turkey.
Haplogroup distributions.
Cinnioğlu et al. (2004) found many Y-DNA haplogroups in Turkey. Most haplogroups in Turkey are shared with its West Asian and Caucasian neighbors. The most common haplogroup in Turkey is J2 (24%), which is widespread among Mediterranean, Caucasian, and West Asian populations. Haplogroups that are common in Europe (R1b and I; 20%), South Asia (L, R2, H; 5.7%), and Africa (A, E3*, E3a; 1%) are also present. By contrast, Central Asian haplogroups (C, Q, and O) are rarer. However, the figure may rise to 36% if K, R1a, R1b, and L—which infrequently occur in Central Asia but are notable in many other Western Turkic groups—are included. J2 is also frequently found in Central Asia, a notably high frequency (30.4%) being observed among Uzbeks.
The main percentages identified were as follows:
Other markers that occurred in less than 1% are H, A, E3a, O, and R1*.
Further research on Turkish Y-DNA groups.
A 2008 study took into account oral histories and historical records. The researchers went to four settlements in Central Anatolia and chose a random selection of subjects from among university students. 
In an Afshar village near Ankara where, according to oral tradition, the ancestors of the inhabitants came from Central Asia, the researchers found that 57% of the villagers had haplogroup L, 13% had haplogroup Q and 3% had haplogroup N. Examples of haplogroup L, which is most common in South Asia, might be a result of Central Asian migration even though the presence of haplogroup L in Central Asia itself was most likely a result of migration from South Asia. Therefore, Central Asian haplogroups potentially occurred in 73% of males in the village. Furthermore, 10% of the Afshars had haplogroups E3a and E3b, while only 13% had haplogroup J2a, the most common in Turkey.
By contrast, the inhabitants of a traditional Turkish village that had little migration had about 25% haplogroup N and 25% J2a, with 3% G and close to 30% R1 variants (mostly R1b).
Whole genome sequencing.
A study of Turkish genetics in 2014 used whole genome sequencing of individuals. It found that the genetic variation of contemporary Turks clusters with South European populations, as expected, but also shows signatures of relatively recent contribution from ancestral East Asian populations. It estimated the weight for the migration events predicted to originate from the East Asian branch into Turkey at 21.7% (see image).
Other studies.
A 2001 study that looked at "HLA" alleles suggested that "Turks, Kurds, Armenians, Iranians, Jews, Lebanese and other (Eastern and Western) Mediterranean groups seem to share a common ancestry" and that historical populations such as Anatolian Hittite and Hurrian groups (older than 2000 B.C.) "may have given rise to present‐day Kurdish, Armenian and Turkish populations." A 2004 study that looked at 11 human‐specific Alu insertion polymorphisms among Aromanians, Macedonians, Albanians, Romanians, Greeks, and Turks, suggested a common ancestry for these populations.
A 2011 study ruled out long-term and continuing genetic contacts between Anatolia and Siberia and confirmed the presence of significant mitochondrial DNA and Y-chromosome divergence between these regions, with minimal admixture. The research also confirmed the lack of mass migration and suggested that it was irregular punctuated migration events that engendered large-scale shifts in language and culture among Anatolia's diverse autochthonous inhabitants.
A study in 2015, however, wrote, "Previous genetic studies have generally used Turks as representatives of ancient Anatolians. Our results show that Turks are genetically shifted towards Central Asians, a pattern consistent with a history of mixture with populations from this region." The authors found "7.9% (±0.4) East Asian ancestry in Turks from admixture occurring 800 (±170) years ago." 
According to a 2012 study of ethnic Turks, "Turkish population has a close genetic similarity to Middle Eastern and European populations and some degree of similarity to South Asian and Central Asian populations." The analysis modeled each person's DNA as having originated from "K" ancestral populations and varied the parameter "K" from 2 to 7. At "K" = 3, comparing to individuals from the Middle East (Druze and Palestinian), Europe (French, Italian, Tuscan and Sardinian) and Central Asia (Uygur, Hazara and Kyrgyz), clustering results indicated that the contributions were 45%, 40% and 15% for the Middle Eastern, European and Central Asian populations, respectively. At "K" = 4, results for paternal ancestry were 38% European, 35% Middle Eastern, 18% South Asian, and 9% Central Asian. At "K" = 7, results of paternal ancestry were 77% European, 12% South Asian, 4% Middle Eastern, and 6% Central Asian. However, results may reflect either previous population movements (such as migration and admixture) or genetic drift. The Turkish samples were closest to the Adygei population (Circassians) from the Caucasus; other sampled groups included European (French, Italian), Middle Eastern (Druze, Palestinian), and Central (Kyrgyz, Hazara, Uygur), South Asian (Pakistani), and East Asian (Mongolian, Han) populations. 
A study involving mitochondrial analysis of a Byzantine-era population, whose samples were gathered from excavations in the archaeological site of Sagalassos, found that these samples were closest to modern samples from "Turkey, Crimea, Iran and Italy (Campania and Puglia), Cyprus and the Balkans (Bulgaria, Croatia, and Greece)." Modern-day samples from the nearby town of Ağlasun showed that lineages of East Eurasian descent assigned to macro-haplogroup M were found in the modern samples from Ağlasun. This haplogroup was significantly more frequent in Ağlasun (15%) than in Byzantine Sagalassos, but the study found "no genetic discontinuity across two millennia in the region."
A 2019 study found that Turkish people cluster with Southern and Mediterranean Europe populations along with groups in the northern part of Southwest Asia (such as the populations from Caucasus, Northern Iraq, and Iranians). Another 2019 study found that Turkish people have the lowest fixation index distances with Caucasus population group and Iranian-Syrian group, as compared to East-Central European, European (including Northern and Eastern European), Sardinian, Roma, and Turkmen groups or populations. The Caucasus group in the study included samples from Abkhazians, Adygey, Armenians, Balkars, Chechens, Georgians, Kumyks, Kurds, Lezgins, Nogays, and North Ossetians.