Derbyshire is a sociologist and a prison doctor from what I have read, he would know these things better than anyone, he sees it on a daily basis.
Actually, Derb is a math guy. I suspect you are thinking of Theodore Dalrymple, who is also a fantastic writer!
You’re referring to the excellent British writer Theodore Dalrymple. I think his latest book is”Life at the Bottom”.
You are confusing John Derbyshire with Theodore Dalrymple.
You are confusing him with Theodore Dalrymple. Derbyshire is a mathematician with a Chinese wife and Amerasian children.
I think you are confusing Derbyshire with Theodore Dalrymple (former prison doctor.) Derbyshire is a very skilled mathematician.
Both are British.
P.S. Now labeled “racist” by NRO, Derybshire is married to a Chinese woman, the mother of his children. “Racist” is of course a selective term of abuse.