I have a 13-year-old daughter who swims in a competitive local national development group. I have been volunteering as a timer at her swim meets since she was six or seven years old. When the children were younger, there was not a noticeable difference between girls’ and boys’ times. But somewhere between ages 11 and 12, the boys begin to swim faster than the girls. By 13, most of the boys are obviously bigger and more muscular than the girls and they swim faster races. It would be demoralizing for the girls to have to compete against the boys as they know they can’t win.