On the third day of the End of the Oregon Trail basketball tournament, the 2,000-girl extravaganza that kicks off the West Coast N.C.A.A. women’s summer scouting season, Jaime Nared walked into the upstairs gym at Oregon City High School, her pink-and-white athletic sandals shuffling like slippers, her face so smooth and calm she appeared to have just woken up. July is one of the few times of the year when Division 1 coaches are allowed to comb the country, watching elite youth games, filling their legal pads with notes on who has a smooth jumper or is a strong rebounder, who might turn out to be the next Candace Parker, the next big thing. N.C.A.A. rules prohibit coaches from talking directly to players. Shirts and bags with college logos announce their presence, and silence only adds to the mystique. Until this past spring, Jaime had been quietly going about her life, as unnoticed as a mocha-skinned 6-foot-1 12-year-old can be in predominantly white Portland, Ore. It was then that she found herself at the center of a controversy about sports and gender: she’d been kicked off a boys’ basketball team for being too good.

Now, as she entered the gym, Jaime didn’t even glance at the 25 coaches lined up on folding chairs. She just walked over to the bleachers and bent her lanky frame into a seat alongside her best friend, Kailee Johnson, who is 6-foot-2.

“Did you get your bottom ones off?” Jaime asked, lacing her size-11 1/2 basketball shoes. Kailee pulled down her lower lip, showing off her braces-free teeth and her sparkle-and-rainbow manicure. Just six weeks earlier, Jaime finished sixth grade and Kailee finished seventh, but both have such prodigious basketball talent that they play with high-school girls in an elite youth program called Team Concept. Their saggy, light blue uniforms almost masked the fact that while the older girls already possessed the full complement of curves and muscles that come with puberty, Jaime and Kailee did not.

Just...