One question often raised is: how robust can ancient DNA studies based on a few samples be? The answer is that it would be a mistake to look at one genome as something akin to say, a person in a survey answering a question as Yes or No.
A single genome carries within itself the genetic track record of a person’s ancestors going back thousands or tens of thousands of years.
It is fully clear that Arya migration has happened into India but Brahmins and Upper castes dislike it because they find themselves an outsiders. And India media is controlled by upper castes so they simply deny this theory.
Aryans has marked locals Raksha, demons, etc due to their complexions and to belittle them. They are backwards due to that history. Those locals needs their voice.
In general, we all came from Africa and spread from there. Earlier evolution was happening so humans are different looking at different place. But, later around 40,000 years ago it is slowed down and around 10,000 it is almost stopped.
Origin of Caste System in India:
Aryans divided themself into three categories - Warriors, Priests, and Vaisyas. Vaisyas includes Craftsmen and farmers. Warriors and Priests used to fight for first place but Brahmans come victorious. Later, sons of each profession practiced what their father practiced. This way caste or Jati was formed.
These Aryans who has defeated locals do not want to include within themselves but kept them for their work. These locals were put into Shudras. Sudra are of two types - Original Locals, and those Aryans who married with locals.
Other invaders who invaded India after Aryans were given Kshatriyas status but warriors among locals were not given the same status.
OBC is a part of Aryans is not looking digestible. That short article may be not neutral. Need to check more.