Soy beans are rich in isoflavones, a naturally occuring
estrogen-like compound. They are usually recommended for women
going through menopause to ease their sysmptoms (to supplement
their decreasing estrogen production)
Maybe that's why some say males shouldn't take too much soy bean
products 
.
Then again, many things in our envt are contaminated. Eg.
whatever hormones found in birth control pills excreted into
our sewage system makes it way back to us in the form of drinking
water. I don't know if the filtering systems they have now can
filter out synthesized hormones?
And poultry too contain all sorts of chemicals & hormones -
steroids, estrogen etc etc..I guess that's why the male sperm count
(& overall fertility of the general population) has been
decreasing with each generation..