As a general rule, women have a natural disadvantage to men in running; the best women cannot compete with the best men. This is why women runners compete against other women and men against men. But when it comes to sex, the anatomy we’re born with, and gender, the social role we adopt, it’s not always clear that a person fits neatly into one of two boxes: man or woman.

The obvious case is transgender athletes: athletes who were born with the anatomy of one sex, but whose gender identity is aligned with the other, resulting in their transition from their sex at birth to the other. Transgender athletes may transition medically, surgically, or both. At what point is a transgender woman biologically woman enough to compete as a woman? In the past, governing bodies of sport have required surgery before a transwoman could compete in a women’s race. Recently, the International Olympic Committee has said it plans to move towards a ceiling of testosterone levels for women athletes, because higher levels of testosterone in men is the main reason men are generally faster than women runners.

But a ceiling on testosterone levels could knock some women out of international competition, women like Caster Semenya and Dutee Chand. Both were born with female genitalia, but also with rare genetic conditions that cause a natural elevation of their testosterone levels. This condition is generally known as intersex. Recent rulings by the international governing body of track and field, IAAF, have allowed Caster Semenya to compete without taking medication to block her testosterone levels and she has been dominating the international scene in the 800 meters. Should intersex athletes like Caster be allowed to compete in women’s races without taking testosterone blockers?

While it has yet to establish binding rules, the IOC has proposed that transgender women be allowed to compete in women’s competitions if their testoserone levels fall within a range typical of ciswomen and requires the same of intersex athletes, meaning the IOC would require intersex women to take medical or surgical steps to lower their testosterone or be forced to compete as men or not at all.

What say you? When should transwomen and intersex women be allowed to compete?