Hi Anon and thanks for your question!

Beverages made from soy contain chemicals called isoflavones which have estrogen-like effects on the body. They are sometimes called phytoestrogens meaning estrogen that comes from plants. The isoflavones can bind to estrogen-responsive areas on cells in the reproductive organs, liver, brain and other tissues. Although these isoflavones can mimic the effects of estrogen, in some tissues the isoflavones block the effects of estrogen.

If you would like detailed information on this please go to this report from the Journal of Nutrition for more information. Hormonal Effects of Soy In Premenopausal Women and Men. 

Hope that helps!

Pat