When looking at it with full perspective, lol, the biological idea given above sounds (as biological theories always do) frankly one-dimensional and dismissive. Science doesn't even understand growth and development generally anyway, yet alone for such a minority group - and of course most asian men will not be transexual. I am western European, totally in origins, yet I also have neat facial features and relatively small hands and feet for my height, yet my Testosterone level was within normal range lol.
I don't think simple answers ever work regarding anything to do with life. Nowhere is this more evident than in the attempts to understand why transexuals feel as we do in the first place - I have read reams of nonsense on this subject from expert sources - none of which resembles or explains it adequately.