That's a really interesting question. Soybeans are a source of chemicals known as phytoestrogens (fye-toe-es-trow-jens). These chemicals affect the chemical signaling system in our body, known as the endocrine system. As you can imagine this might have an effect on how our bodies work.

There have been a few studies that have shown that testosterone (the "male-ness" hormone) is lower with more soybean ingestion in men. In the studies, this actually was good because it protected the men against prostate cancer. The more soybeans they ate, the less likely it was they would have prostate cancer.

The idea that it makes men more feminine has not been shown. Although soybean may lower testosterone levels, this may not automatically make a guy more feminine. The endocrine system is very complex and how things interact overall is not understood well.

There have been a couple of studies looking at breast cancer in women and soy product intake. The area is very controversial. Soy product intake has been linked to tumor growth in animals but it is also possible that in humans that this might not be the case. In fact soy products may help prevent cancer. A lot more research must be done to figure this out. Sorry I can't answer your question better, but this subject is under investigation right now and even the experts in the field don't really know.