Story concept: Competitive athlete siblings

An idea for a story that is on my mind, if anyone is wanting a prompt or inspiration.

Very athletic family, always striving to be the best. While the daughter is very successful she can just not quite reach the level of her brother and is sick of all the praise he from their parents while she is constantly looked over despite all of her achievements and trophies. In trying to find out what could be giving him an edge over her, and how she could sabotage or undermine him, she develops a fascination and hatred for his balls for making him the man he is. Cue some sort of “accidental” or fully intentional ballbusting that results in him losing that advantage. Maybe the mother finds out why her daughter is suddenly surpassing her brother and decides to use similar tactics on her husband - after all they are still competitive with eachother, and it’s not like she needs or wants any more children