My daughter is barred from competing in school sports in at least a dozen states. It's all because she's trans.

• My daughter is bad at sports but despite that, she is barred from school sports in several states.
• It all boils down to her being transgender.

At the start of high school, our daughter was tiny — 4-foot-10 and 75 pounds. Yet more than a dozen states in the US, including Florida, Texas, and Arizona, perceive her as such an athletic powerhouse that she's barred from girls' sports before a single tryout.

In fact, she's barred from tryouts.

Here's the kicker: She's a terrible athlete. She can't overhand serve. She gets bored on defense. She doesn't like to put her face in the water to swim.

Our daughter happens to be transgender, and that's the reason she's barred from girls' sports in these states. She also happens to be smart and funny and was raised in a family of athletes. Her father was a Division I college athlete, and her older brother just finished up a Division III college career. Her other two siblings excelled on the soccer field. In high school, I was the second-highest scorer on my field-hockey team.

When legislators bar transgender athletes, I get the feeling that they're envisioning a strapping athletic boy in a dress. In fact, their comments often indicate that they're not imagining someone who's transgender at all but some sort of imposter who wants to dominate girls sports teams while faking being trans.

Transgender athletes are rare the same way great athletes are rare

If you look at the general population of high schoolers, great athletes are rare. This is also true of transgender students. While much attention has been given to the rare excellent transgender student-athlete, almost no one talks about the vast majority of trans students, the ones who do not excel in sports but who might be kids who just want to have the typical high-school experience of being on a team — fresh air, exercise, new friends, and the love of a lifelong sport.

While Republican lawmakers didn't think about trans girls like my daughter, whom no one would ever presume to be trans and who isn't a threat to anyone's playing time, they also didn't think about how their laws could affect girls who are not trans. They didn't imagine the athlete who gets accused of being trans because, perhaps, she's a little taller and broader in the shoulders than her teammates and dominates in a sport.

In Utah, this is what happened when the parents of two girls who didn't win a sports competition accused the winner of being transgender. Officials at the Utah High School Activities Association combed through the winning student's school records dating to kindergarten and it was confirmed she was assigned female at birth; the winning student and her parents were not informed that she was under investigation or that strangers were digging for incriminating evidence of a transition.

The US loves school sports

As a culture, we love high-school sports. We idealize what they do for our kids, and I believe that playing a sport, especially on a team, can be incredibly important.

What transgender high schoolers are denied when we bar them from playing a sport are all the things that we say we believe in about the importance of sports. They lose what many people value as the best part of their high-school experience. They lose a team, lifelong bonds, community, friendships, and a coach who believes in them. They lose a feeling of contribution, of being of use, of school spirit; they miss out on lessons of resilience and self-confidence. They lose connectivity to physical activity and the opportunity to build healthy lifelong habits.

Depression and suicide risks for this community are staggeringly high. Fully aware of these facts, schools are further isolating trans kids and taking away one of the strongest recommendations for positive mental health — exercise.

As for my daughter, she lives in a state that has bandied about barring transgender students from sports, but it didn't become law. She attends a private school where sports are mandatory because the school believes in all the upsides of being on a team, as do I.

Without the law barring her, she grudgingly took up tennis. While she's still a benchwarmer, she likes the sport and she's made friends and feels more connected to her school community. She's out there on the court, smiling and joking around and having fun. One could say she's pursuing happiness, which should be her right as an American.

Carolyn Hays is an award-winning, critically acclaimed, and bestselling author who has chosen to publish "A Girlhood: Letter to My Transgender Daughter" under a pen name to protect the privacy of her family. Her novels have been published by Hachette, Simon and Schuster, and HarperCollins.