In tournament, I have sparred with people my own sex but a decade younger and I have sparred with grown men, it's about rank and weight, not sex. In club sparring, I have sparred my 8 year old son, my husband (much to the delight of all watching), women my age, little girls, and one woman I will politely call "venerable." In a club of 25, we have 3 women, two grown men and the rest are little boys. If we didn't mix up ages and sexes, no one would spar. I told one student a while back who made fun of a karate-ka for sparring a girl that "girl or boy, we are all karate-ka, and all due the same respect." Why should we treat each other any different because of what dangly bits we have? Maybe because I am a MAmom, I just don't see the issue. There aren't girls and boys on the mats, there are combatants, martial artists, students. That said, and speaking strictly as a mother now, I DO completely understand what her mother might be thinking. I can't imagine it's easy for her to watch her daughter get slammed to the floor by a guy (even if she slams back). perhaps having mom talk to other girls who have competed may help. If older women or girls who have done this type of competition could talk to mom, help her to understand, she may be willing to make a compromise.