Well, were their Moms still smoking at this point, or did they give it up after pregnancy? Think that might have anything to do with it?
The best way to test it would be to study adoptees whose bio mothers smoked, but whose adopted parents didn't.
Mr. Cat's mom smoked during pregnancy and around him all his life. Not surprisingly, he is a smoker still. He's never NOT had nicotine.
I am sure it is the type of research that can have whatever outcome they were looking for.