The BBC covers a study that suggests that social status depends on grandparents, not just parents.

“It may work through a number of channels including the inheritance of wealth and property, and may be aided by durable social institutions such as generation-skipping trusts, residential segregation, and other demographic processes.

Pointer from Jason Collins. He also has more.

My first thought is “mean reversion.” That is, suppose that you have two genetic types–rich and poor, call them R and P. Suppose that R and P each have children. Some of R’s children get unlucky and some of P’s children get lucky. Now the grandchildren of R still carry the R gene, so unless they are unlucky, they will revert to being rich. And conversely for the grandchildren of P. So you could observe a strong grandparent effect, based on mean-reversion and genetics alone.

But I have not read the paper.