From a previously posted article, "The Potential Effects of Soy, and How it Might Decimate the Health of Your Unborn Baby and the Fertility of Future Generations":

"neonatal exposure to genistein changes the level of immune response in the mouse oviduct, known as mucosal immune response. Some of the immune response genes were altered beginning from the time of genistein treatment, while others were altered much later, when the mouse was in early pregnancy. Together, those changes led to harmfully altered immune responses and to compromised oviduct support for preimplantation embryo development, both of which would likely contribute to infertility."

and also

"Earlier research has also found that the compound genistein impairs sperm as they swim toward the egg. Even tiny doses of the compound in the female tract could destroy sperm, which would impair your ability to conceive in the first place."

But the article this post is in response to, "This Humble Food Extract Puts Bone Drugs To Shame", says:

"Genistein has been extensively researched for its potential therapeutic role in osteoporosis prevention and treatment, as well as a mind-boggling 140 additional health conditions. It is likely the main reason why soy, and particularly fermented soy, has been regarded as both a food and a medicine in Asian culture. What makes this finding so groundbreaking is that genistein is a food derivative, whereas the three categories of drugs compared to it in the study are evolutionarily and biologically alien chemicals (xenobiotics) with profound, unintended adverse health effects."

So apparently, only people beyond reproductive age, in danger of losing bone mass, should consume products containing genistein, including soy.

Or, alternatively, my head explodes...