Well, looks like you have some idea. Soy phytoestrogens can bi  246  nd to estrogen receptor sites (in the same way that BPA can) and the not so 'bro science' theory is that if the receptor sites are occupied by 'soy' then the naturally produced estrogen is going to go and femme up the place elsewhere. There's then the "Oh look at the Chineseses and how much soy they eat and they're all manlets". Recalling what I've seen in the actual science, there's no significant difference in anabolic effect between whey and soy protein from a supplementary perspective as long as you're getting enough protein and calories overall. I have s  7ffa  een one study that suggested some negative outcomes in male/female infants when they were followed up in around adolescence...something to do with growth trajectory in both height and muscle mass. It was a very obscure study but did suggest it wasn't great...for infants. I think there's also some evidence to suggest transient depression in testosterone post soy consumption but that might just be the general insulin/test curve being misrepresented as 'soy protein bad'.