And then there are the little girls who turn into boys at puberty.
They are called Guevedoce.
"Puberty can be an awkward time for anybody, but spare a thought for the Guevedoce children of the Dominican Republic, who literally appear to change their sex when they hit adolescence.
As covered by Michael Mosley in the 2015 BBC series, Countdown to Life: The Extraordinary Making of You, the remarkable case of the Guevedoces is a condition that affects just over 1 percent of the boys born in Salinas, a remote village lying in the southwest of the Dominican Republic.
Guevedoces (literal translation "penis at 12") - who are also called "machihembras", meaning "first a woman, then a man" - appear to be completely female at birth and are brought up to be little girls.
"When they're born, they look like girls with no testes and what appears to be a vagina," wrote Mosley for The Telegraph back in 2015. "It is only when they near puberty that the penis grows and testicles descend."
After the developments of puberty, Guevedoces grow up to be fully functional males in their society, although some telltale signs do give away their unique biological heritage.
"Apart from being slightly undersized, everything works and the Guavadoces normally live out their lives as men," wrote Mosley, "albeit with wispy beards and small prostates.""
In This Remote Village, Some Boys Don't Grow a Penis Until They're 12
Must be pretty awkward for Christianity to deal with this. Would bathroom laws force these men to use the women's bathrooms for life because that's what they were identified as upon birth?
"The condition is not isolated to just the Dominican Republic, it's also been observed in Turkey and New Guinea."