Oh, I hope I don't come off as sounding terribly sexist, but for me it's when I hear about young boys on wrestling teams having to wrestle girls, or another inter-gender contest of physical prowess, like martial arts. You can feel how you like, but the majority of his peers are most likely going to be very unforgiving, no matter what happens- either he "beat a girl, no big deal", or he gets "beat by a girl", which during formative years can be especially traumatic (This is pulled from personal experience and accounts, mainly, so don't look to me for statistics.).
Never mind that it should be seen as one grappler vs. another in the same weight category, which is what it would be, all things being equal, which they are sadly not- most girls in these weight categories are older, and likely more physically mature, and often in martial arts, girls a class higher are pitted against lower ranking boys.
I'm having some problems dealing with what defines masculinity at the moment, especially in my own life, and I always believed that physical prowess in combat sports was heavily dominated by men. If anyone knows more about how it really is with wrestling, as in, actually wrestled through college, and has seen whether Youtube's overwhelming bias in favor of women in inter-gender matches (seriously, there are like one match where a boy wins for every two-dozen where a girl wins) is really reflective of the sport, I would love to hear from you, and maybe chat about it if you're amenable.
And please, no hostilities! I meant do offense, and am just trying to open a dialogue here, so I could do without rudeness or sarcasm.