It has nothing to do with religion IMO.
Education is given a lot of importance in southern India, that could have helped a tiny bit, but apart from that I don't see how it is relevant.
Dr Abdul Kalam is widely revered in India for his contributions to rocket propulsion, pretty sure he was good at math & physics as well.
Come from the same region as these folks. There is no correlation to religion in a lot of this. I studied in Govt. institutions where no one cared about a lot of religion , it was just race to the top.
I understand there is a lot more polarity now , trust me this does not have a thing!. The most inspirational engineer all of us looked to was Dr. APJ.
Peer groups matter
I am not sure whether there is some research about it why is it like that? some diet/belief or some other matter?
Happy to learn more about it.