[dhosek]

Or it could be that children of PhDs come from an environment where they know what’s required to get a PhD. Neither of my parents had bachelor’s degrees. I had no idea that any PhD worth its salt would be something that the PhD student was paid to attend rather than would pay to attend.

And as an aside, my cousin’s husband has a PhD and yet none of his kids have graduate degrees, while in my family, out of three brothers, there’s a DVM, and MS and me with a MS and MFA.

[crackercrews]

No one is debating whether there are environmental factors. Surely there are. The point is that there are also likely heritable factors. These cannot be erased. And without measuring them, we don't know how much of a "problem" it is that many professors have PhD parents.