'bro science' - apparently there's chemicals in soy that have similar names to estrogen. A bunch of people claim that's why Asians are 'less manly' or something. I've not seen any credible evidence that this is any more scientific than 'neuro linguistic programming' (or the idea that the average asian dude is 'less manly' for that matter.)

On a more personal note, I'm a big white guy who looks like a big white guy who was raised on more soy than your average Asian dude (hippy parents.) I call bullshit.