There is a review of the book in this months Archaeology Ireland. I haven't got it in front of me but from memory i think it does go into genetics.
Just looking at the amazon link to the contents.
Chapter 8
Skulls, Blood and Genes - 215 - 243
So he must go into a bit. I'm looking forward to it anyhow - Archaeology Ireland give it must read status which I've never seen them give to any book before.