I haven't read the book, because I'm highly skeptical and refuse to give Dr D'Adamo my hard-earned cash. Unless he can clearly demonstrate that the genes for metabolism are linked very closely to the genes for ABO blood cell antigens, it's a load of hooey. (And I'm pretty sure it's the latter, from what I learned in my 2nd year genetics course.) This is because genetic traits are inherited *independantly* from one another, with the exception of those that are literally *very close together* on a chromosome - and even then, it's not guaranteed, it's just higher probability. So just because you got type A blood (for example), doesn't mean you inherited any specific metabolic traits along with it.

My not-so-humble opinion.