INDIANAPOLIS >> The calls to high school sports officials from athletic directors and administrators began several years ago and have only become more frequent and difficult: How are you handling transgender students who want to play sports?

With widespread disagreement over where the line should be drawn between sexes for purposes of athletic competition, the question has challenged the people who set rules for Olympics sports and those who govern college sports in the United States. At the high school level, the issue has been even more vexing.

“Quite frankly, I don’t think anyone has it exactly right because if they did, everyone else would just do that,” said Jamey Harrison, deputy director of the governing body of high school sports in Texas. “If you look at what the NCAA is doing and what the Olympics committee is doing — and those are different because they’re largely dealing with adults, versus we are working with minors — it doesn’t seem like anybody has landed on something that is universally applicable.”

The issue has touched off debate among coaches, athletes, parents, doctors and medical ethicists. Established guidelines at the youth level that address things like hormonal treatment and sex reassignment surgery are nonexistent.

Harrison said the issue first emerged in Texas in 2012, when the state governing body — the University Interscholastic League — had rules that required female athletes to compete on girls’ teams and males on boys’ teams, but no rule that addressed how to decide someone’s sex.

Transgender students — those who identify as a different gender than their biological sex — did not fit into an existing category.

“We had more and more schools who said, ‘We have a student who is transitioning or transitioned,’” Harrison said in a phone interview. “I think without question, it has become much more of a common issue than it had previously been. There are strong feelings on all sides and people are very passionate about their stance. It has been a challenge.”

With no national governing body laying down rules, individual states have navigated the issue independently, weighing the shifting beliefs of schools, parents and athletes.

In Texas, superintendents from member schools voted in a referendum that the governing body should use birth certificates to determine a student’s sex. Indiana uses anatomical sex to determine what team a student can play on. Other states, including California, have adopted rules that allow students to use bathrooms and locker rooms and participate on the teams that align with the gender the person identifies as.

The issue is particularly nettlesome with individuals who have transitioned from male to female because of the belief that they might still have a physical advantage until their hormone therapy — which not every transgender person chooses to have — is complete.

There is no reliable data on the number of transgender high school athletes. Only about 0.6 percent of the adult population identifies as transgender, according to federal data from 2016. Researchers from the Williams Institute, who conducted the study, reported that 0.56 percent of adults in Indiana reported identifying as transgender.

In Texas, 0.66 percent of adults said they identify as transgender, the fifth-highest percentage in the country (behind Hawaii, California, New Mexico and Georgia). Still, transgender children are considered an at-risk minority outside of sports. According to The New England Journal of Medicine, the rate of suicide attempts among transgender people is 40 percent, compared with 4.6 percent among those who are not transgender.

Relatively new policies are already being massaged and amended. In July, the Indiana state association voted unanimously to adjust its surgery requirement. It now no longer requires transgender students who are transitioning from female to male to have sex reassignment surgery to compete in the gender with which they identify. But that stipulation is still in place for someone transitioning from male to female.

The group asserts it is acting in the name of fairness, but transgender rights activists accuse members of simply not wanting transgender people to participate, out of fear that those athletes will have an unfair advantage.

Olivia, who asked to be identified by first name, is transgender — born with male sex organs but now identifying as female. A high school sophomore in Indiana, she kept her gender a secret from her coaches while playing freshman tennis so that she could play on the girls’ team. A handful of her teammates know that she is transgender, but it had not come up as a problem. Olivia’s mother, Melissa, said that she did not think the tennis coach knew that she was not biologically female.

When the state sports association did not loosen its surgery requirement for male-to-female athletes, Olivia and her family decided to fight the ruling.

“Imagine you are practicing your favorite sport one day when somebody comes and tell you that you are not able to participate on the team,” Olivia wrote in a letter to association’s committee members. “So many emotions are swirling through your head: confusion, anger, embarrassment. Not only does this take away your right to play, but it takes away something that defines you.”