Billy the Fish
Technocrat
That would be soya milk, not soy, no?
I think it is more to do with the theory that high soy levels in diets can lower testosterone. This has been attributed to low sex drives amongst males in some Asian countries.
This is the correct answer.
Bodybuilders avoid soy products because it lowers testosterone. At some point it's been turned into an insult to describe effeminate men.