Erm  Isaac Azimov writes er, rather amusingly about this, he says why did, why did Weismann bother, he said Weismann was Jewish, of course, Weismann knew that since time immemorial, er, Jewish little boys have been having their foreskins chopped off, Weismann only had to look at his own children, when they were born, to see that even Jewish little boys are born with foreskins.