I was reading an article about how Sam Kerr (the fantastic Australian and Chelsea women's footballer) used to play Aussie Rules football with boys until the age of 12.
Back then, it was obvious to her Dad and her Aussie Rules coach that the difference in biology between Sam and the boys made it unsafe after this age. Aussie Rules is far more brutal than standard football ("soccer") but if this was so easy to say back then, why are some sports and some countries still failing to acknowledge it now?
From the article:
"But as good as I was out on the field, and as much as I loved playing the game, the physical differences between the guys and me eventually became too pronounced and the play was too rough.
“One day, I came home from a game with yet another black eye and bloody lip, and that’s when my dad and brother both said, ‘Nup, this isn’t happening anymore’.
"I was getting battered around so much out on the field that it was getting to be a big problem. Dad and my coach both sat me down then and said it was getting far too dangerous for me to continue to play"
Link to article