I assure you I am in good faith, I understand the topic is sensitive, but I don't know what in my comment would suggest I am in bad faith. I think it is likely that there are differences in IQ between the castes, just as there are other physical differences, and that the higher caste would have on average higher IQ since IQ is a decent predictor of social economic success in most contexts. Perhaps people familiar with the Indian education system can chime in about standardized test scores broken down by caste - my recollection from years ago is that there are differences.

By segregated reproduction I just mean that most likely mate selection is done within cast, so any difference in IQ between castes is likely to be slow changing as there is little gene exchange between groups. Something similar happens in US society where there is growing stratification along IQ lines.