The stickiness of class - Part Deux

Gregory Clark, the author of 'The Son Also Rises: Surnames and the History of Social Mobility' discussed earlier, has an article in the New York Times that raises some interesting and some questionable claims. The interesting parts relate to his main thesis that it can take several centuries for a high class or low class family to regress to the mean i.e. become average. Class advantage or disadvantage is hard to shake. The questionable part of his article is his insistence that much of this effect is related to genetics. It is unclear to me why people with no training or obvious knowledge of genetics are so taken with genetic determinism. There are multiple critiques of his position in the comments but the most obvious is that he has no information about the marriage partners of the males whose names he follows through history. If you are going talk breeding you have know who bred with who.