So, one question that might determine whether aliens have sex, Otto said, is what their cells look like.

“Do they evolve nuclei or other ways of protecting their DNA inside a series of membranes?” she said. If extraterrestrial life is equipped with nuclei, they might benefit from sex.

Another thing that Planet Xenon might need to prompt the evolution of sex is change.

Sex is very beneficial to organisms because the environment is rarely static, Otto explained. Offspring may have to deal with challenges that are slightly different from those of their parents’ generation. As long as change is a constant, genetic variation is helpful.

If an alien planet had, for some reason, constant weather, temperature and other environmental factors, “sex would have mainly costs, but no benefits,” Otto said.