A surprising linguistic phenomenon is that the populations in Europe, Iran, Armenia and North India trace their languages back to the same root. What is surprising in that matter is that the other populations in the Middle-East speak Semitic languages (Arabic, Hebrew) which are unrelated to the above mentioned languages spoken by Iranian peoples (Persians, Lors, Bakhtiaris, Gilakis, Mazandaranis, Kurds, Balouchs, etc.) and Armenians 
The traditional point of view on this issue is that proto-Indo-Europeans migrated from East Asia and separated in Central Asia (North-East of the Caspian Sea), one group going to Iran and India and creating the Indo-Iranian (Aryan) subfamily and another one migrating to Europe creating Latin, Germanic, Slavic and other European languages. 
Source: BBC Persian
In that case, peoples currently living in these areas should be related, as they come from the same ancient tribe (Indo-European tribe-s) and this is what linguistic theorists based themselves on to conclude that these people constituted a tribe that separated in Central Asia.
The problem is that recent genetic studies done on Iranians show that their ancestors could not have come from Central Asia and that the current Iranian people are descendants of the peoples living in the Mesopotamia/Iranian plateau region ~10,000 years BC. 
According to the most accepted theory about Indo-Europeans, they arrived from North-East Iran and then composed the three main ancient Iranian peoples Greek historian Herodotus wrote about: the Persians, the Medes and the Parthians. 
However, if this is the case, how come no trace of Central Asian genes is found in the current Iranians’ DNA? One can argue that this is because they were mixed with other populations, but according to geneticists, traces of very distant and unique ancestors can be found in DNAs.  There should thus be a trace of Iranian ancestors in Central Asia.
As this is not the case, we can conclude that these Persians, Medes, Parthians and other Iranic peoples (Aryans) living on the Iranian plateau between 500 and 1000 BC did not come from Central Asia but were people already living there, along and mixed with the other peoples such as the Sumerians, Babylonians, Elamites, Assyrians and others. That’s why there is a unity in the country’s peoples, whether they are Iranian Persians, Iranian Azeris, Iranian Arabs, even though they do not speak languages from the same families, they are closely genetically related. 
Even genetic tests on today’s Indians show no relation to the Central Asia region or to tribes coming from there. 
Another issue is that some people like the Kassites and Hittites already had Indo-European roots in their languages and names before the arriving of the assumed wave of Indo-Europeans into the Middle-East (Iran) and India from the East and Caucasia.
All these points lead to the same conclusion, Indo-European languages had already developed in the region and there was no immigration wave coming from other parts of Asia. The theory that Indo-European languages first developed in Anatolia or Mesopotamia seems to be right after all. Indeed, this theory was first developed by Colin Renfrew in 1987  mainly based on archaeological events (the spread of farming) but was badly received by the anthropologist community . However, genetic tests made nowadays seem to prove his theory, now backed by other scholars such as Quentin Atkinson. 
Moreover, Turks are genetically far from other Altaic-speaking populations such as Mongolic peoples, even though traces of Altaic peoples can be found in them, proving the Altaic invasion of Turkey and the imposition of their language.  Furthermore, Turks spoke Indo-European languages before the transformation of their language to current Turkish (Altaic). 
In conclusion, it seems that Indo-Europeans first developed in Anatolia and around Mesopotamia, spread to the East to reach the early Iranians and Indians thousands of years BC and spread to the West to reach Europe.
This explains also the stable genetics of Iranians and Indians throughout History, phenomenon also observed in Levantine people (Lebanese, Jordanians, Palestinians, Syrians) who trace their roots back to thousands of years ago in the Levant.  This also proves that the Arab invasions and the spread of Islam did not change the genetics of the indigenous people.
Populations of the Middle-East are actually quite close to each other and are all descendants of the ancient peoples who lived around Mesopotamia thousands of years ago, developing the first cities, first agricultural systems and first civilizations. The only part with a significantly different genetic composition is the Arabian peninsula (Saudi Arabia, Yemen, etc.)
In my opinion, the reason why linguists started the Indo-European myth asserting that these languages come from tribes who originated in central Asia and migrated to Iran and India for one part and to Europe for the other part comes from the racial-superiority-justifying minds of the 19th and 20th centuries. Theorists preferred to believe that nomadic tribes had migrated from Asia than accepting the fact that their languages trace their roots back to the Middle-East, the cradle of civilization, the place that also gave birth to the Semitic languages, and to the most important inventions and developments of Ancient History.