On pages 54-55 of Daniel Seligman’s book A Question of Intelligence, he reveals Arthur Jensen’s little known interest in India:

In his early years, Jensen was being pulled in still another direction.  While in high school, he developed an enthusiasm for Gandhi and, incredibly found time to produce a book-length manuscript about the Mahatma.  Under Gandhi’s influence,  he also became a vegetarian.  That did not last too long, but Jensen retains an interest in Indian culture and customs–and food.  When he bought a lakeside vacation home several years ago, he put in a second kitchen so he could prepare Indian dishes without getting in his wife’s way.

I asked Jensen what it was about Gandhi that had attracted him.  Was it, for example, the pacifist message?  “No” Jensen said,  “I can’t say I was ever really a pacific.”  (He expected to serve during World War II but ended up with a medical exemption).   Given his determined advocacy of unpopular ideas during much of his life,  the reason he gives for gravitating to Gandhi seems significant.  The main reason:  “Gandhi’s willingness to go wherever his convictions took him.”

From page 76:

…Arthur Jensen once told me a gripping story about a child in India who was denied a formal education because, as a low-caste “untouchable,” he was not allowed to attend the only school in his region.  The child nevertheless managed to learn a lot by spending hours peering through the schoolroom windows,  ultimately,  figuring out what the teacher was explaining at the blackboard.  He learned to read this way,  which enabled him to pursue an education on his own and qualify for the University of Bombay.  Eventually, he became a distinguished Indian lawyer.  It is hard to believe that he would ever have made these heroic efforts to transform his environment without some genetic head start.

Seligman should have asked Jensen what he thought the heritability of IQ in India was during this period.  In the U.S., the WAIS full-scale IQ correlation of identical twins reared apart is about 0.7 by adulthood, suggesting a genotype-phenotype correlation among adopted Americans is an incredible 0.84 (the square root of 0.7)

But these correlations may be spuriously high, because in America, it may not be genes directly raising your scores.  It could be genes causing you to create an environment that raises your scores, so regardless of whether you were raised in a high or low social class, certain genotypes still end up attending university and joining a stimulating occupations that may prepare them for IQ tests.

But in 1930s India, when the caste system so restricted socio-economic mobility that untouchables were prohibited from even entering school, it would have been fascinating to see an IQ study of identical twins reared apart, because you’d have one person confined to a life of unclean labour, and his identical twin raised in an upper caste becoming a doctor.  Only in the most extreme cases, like the anecdote Jensen cited, would an untouchable have become a professional.  Thus, such a study would have given us a more meaningful measure of heritability.