Who is eligible to compete on women’s sports teams? That seemingly simple question is at the heart of a lawsuit filed last week by three Connecticut teenage girls.

The teens, elite high school runners, have filed a complaint with the US Department of Education arguing that Connecticut’s policy on transgender athletes has disadvantaged them on the basis of their biological sex. Connecticut is one of at least 19 states that allow athletes to compete according to their gender identity without restriction.

Selina Soule, the named plaintiff in the case, received national attention last winter when she barely missed qualifying for New England regionals in the 55-meter event at the Connecticut indoor track championships. Andraya Yearwood and Terry Miller, both of whom were born male, finished first and second in that competition. Soule argues that she would have qualified had Yearwood and Miller not been allowed to compete.

Soule sees the issue in terms of lost opportunities. Yearwood and Miller see it in terms of inclusion. They’re both right.

It goes without saying that transgender students must be treated with respect and included in all aspects of a school’s educational program. But athletics pose a thorny issue, where including some students may mean denying opportunities to others.

The fact is, people who were born male are, on average, physiologically stronger, bigger, and faster than people born female. That is why American antidiscrimination law does not prohibit sex-segregated sports. To the contrary, in order to provide equal athletic opportunities for men and for women, as required by Title IX, schools must provide separate women’s teams. Without them, the majority of athletic opportunities would, inevitably, go to men.

Does this mean that schools should never accommodate transgender athletes? Of course not. At Harvard, swim coaches originally recruited swimmer Schuyler Bailar for the women’s team. But Bailar, who came out as transgender during a gap year before college, joined the men’s team after arriving at Harvard, and competed for four years without anyone objecting.

By his own admission, however, Bailar went from being among the top female recruits to the bottom of the pack on the men’s team. Had the situation been reversed, Bailar might have faced pushback.

Bruce Jenner was one of the best athletes of all time competing against men. Had Caitlyn Jenner been allowed to compete against women, most women wouldn’t have stood a chance. Should young women who still rely on Title IX for equal athletic opportunities be forced to compete against the likes of Caitlyn Jenner?

In some women’s sports — sailing, for example — transgender status makes no competitive difference. In other women’s sports, such as field hockey, ice hockey, track and field, or tennis, it does. With respect to running, Eric Vilain, a professor of human genetics at UCLA, told Sports Illustrated, “There is 10 to 12 percent difference between male and female athletic performance. . . . It is a very difficult situation with no easy solution.”

One possible solution is the approach adopted by the NCAA, which prohibits transgender females from competing on women’s teams until they have completed one calendar year of testosterone suppression treatment.

But compromise is impossible when those who raise concerns are shouted down as bigots. That is exactly what happened when tennis icon and LGBTQ activist Martina Navratilova, in an article for the London Sunday Times, questioned the unrestricted participation in female sports of transgender women. The backlash against the 18-time Grand Slam champion was immediate and fierce.

Earlier this year, the US House of Representatives passed the Equality Act, a bill to add gender identity (along with sexual orientation) to the list of categories protected by federal civil rights law. The Senate is unlikely to pass the measure in its current form, and Navratilova has urged Congress to carve out an exception for women’s sports. A Supreme Court ruling next term may take the issue out of Congress’s hands.

The case, R.G. & G.R. Harris Funeral Homes Inc. v. Equal Employment Opportunity Commission, asks the court to consider whether transgender status is already protected by Title VII’s prohibition of workplace discrimination “on the basis of sex.” Because courts generally interpret the identical language in Title IX the same way, a ruling that interprets Title VII broadly will, perhaps inadvertently, mandate unrestricted participation in women’s sports by transgender females.

Whether by statute or judicial fiat, unrestricted “inclusion” for transgender females in women’s sports will necessarily mean fewer opportunities for biological girls. That’s not hate. That’s science. And as the bumper sticker says, “The thing about science is, it’s true whether you believe it or not.”