It was obvious, although not socially accepted. Brahmins-dalits, dravidians-aryans, hindus-muslims christians-jews, when it comes to India they are already mixed! Every is has certain percentage of someone else. Not a good news for many, but hey I dint make this up :-)
Here, a post gives you a breakdown of socially defined races by percentage of actual %age races. Its statistical data, so there will be +/- error, but in general they make a lot of sense to me. If you disagree, send your toothbrush.
Also, he draws few semi-conclusions based on data. One of them is
South Indian Brahmins claim northern Indo-Aryan origins. The genetics certainly bear this out, albeit with some probable admixture with the local substrate. There are many specific questions which can be asked and answered. The Cochin and Bene Israel Jews of the west coast of India clearly do have highly elevated Middle Eastern components of ancestry, though they are highly admixed with the native populations. My own question: do the Nasrani Christians truly descend from Jews? I would have dismissed this outright a few months ago, but I am not sure sure now. The western coast of India seems to have long-standing connections to southern Arabia, so we need to flesh out these patterns in more detail.
And, finally the breakdown