Two Y-DNA Haplogroups are supposed to be connected with Iranic people Haplogroup J2 and R1a1
Haplogroup J2 especially the subcadle J2a is frequently found among almost all groups of Iranic people. In comparison with the Haplogroup R1a1, J2 is not only restricted to geographically eastern and western Iranic populations, but also found among north-western and south-western Iranic populations such as the Bakhtiaris and Mazanderani, as well as geographically north-western Iranic Ossetians. Despite its supposed origin in the fertile crescent, J2a is also found among Iranic populations in the east such as the Yagnobi which are of Soghdian origin as well as the Parsis of India. Beside the relatively high percentage among the Yagnobis in Central Asia, other Iranic populations tend to have a higher frequency of J2a when compared to neighboring Turkic populations. The relatively strong presence of J2a among Ossetians as well as Yagnobis proves distant from the supposed Mesopotamian origin region of J2, are carriers of this Haplogroup.
In the Indo-Iranian context, the occurrence of J2a in South Asia is limited to caste populations, with the highest frequencies found among northern areas of South Asia. Compared with R1a1, J2a shows a more conservative distribution, stronger limited to Indo-Iranian origin groups.
Haplogroup M17, also known as R1a1, has been supposed to be a diagnostic Indo-Iranian marker. The highest R1a1 frequencies are detected in the Central Asian populations of Ishkashemi Tajiks (68%) and Pamiri Tajiks (64%), both groups being remnants of the original Eastern Iranian population of the region. Apart from these two groups, high frequencies of R1a1 are also found in Pashtuns (44.8%) and eastern parts of the Iranian Highlands up to frequencies of 35%, similar to Northern India, while Western Iran based on Iranians sampled (52 Samples from the western part of the country) appears to have had little genetic influence from the supposed R1a1-carrying Indo-Iranians about 10%,to attributed to language replacement through the "elite-dominance" model in a similar manner which occurred in Europe and India. In this regard, it is likely that the Kavir and Lut deserts in the center of Iran have acted as significant barriers to gene flow.
Genetic studies conducted by Cavalli-Sforza have revealed that Iranians have weak correlation with Near Eastern groups, and are closer to surrounding Indo-Europeans speaking populations. This study is partially supported by another one, based on Y-Chromosome haplogroups.
The findings of this study reveal many common genetic markers found among the Iranian people from the Tigris river of Iraq to the Indus of Pakistan. This correlates with the Iranian languages spoken from the Caucasus to Kurdish areas in the Zagros region and eastwards to western Pakistan and Tajikistan and parts of Uzbekistan in Central Asia. The extensive gene flow is perhaps an indication of the spread of Iranian-speaking people, whose languages are now spoken mainly on the Iranian plateau and adjacent regions. These results relate the relationships of Iranian people with each other, while other comparative testing reveals some varied origins for Iranian people such as the Kurds, who show genetic ties to the Caucasus at considerably higher levels than any other Iranian people except the Ossetians, as well as links to Europe and Semitic populations that live in close proximity such as the Arab and Jews.
Another recent study of the genetic landscape of Iran was completed by a team of Cambridge geneticists led by Dr. Maziar Ashrafian Bonab (an Iranian Azarbaijani). Bonab remarked that his group had done extensive DNA testing on different language groups, including Indo-European and non Indo-European speakers, in Iran. The study found that the Azerbaijanis of Iran do not have a similar FSt and other genetic markers found in Anatolian and European Turks. However, the genetic Fst and other genetic traits like MRca and mtDNA of Iranian Azeris were identical to Persians in Iran. Azaris of Iran also show very close genetic ties to Kurds.