Individuals with two X chromosomes "run a dangerous risk of soccer-related-brain injuries".
We all know that the now-obsolete concept of sex is in fact a mere social-construct, and that the proper term is "gender determinate", chosen by each individual as it sees fit. How then is it possible that people formerly known as girls could have brains and skulls different from anyone else? Harumph: another example of sexist white, racist, Trump-loving, fascist scientists attempting to create division in society.
Either these self-identyfing "girls" should change their minds (although soccer balls seem to be doing that anyway) or they should be replaced by more gender-fluid individuals — problem solved.