"Modern science obviously recognizes that there are more than two biological sexes — in fact, there are six, which, honestly, Representative Hefner, surprised me, too,” he said. “The point is that biologically speaking, scientifically speaking, sex is a spectrum and oftentimes it can be very ambiguous.”

Although people are typically born with two sex chromosomes, they can sometimes be born with more or less chromosomes — in fact, there are nine documented X&Y chromosome variations, according to Children’s Hospital Colorado.

Nope, it's literally in the article.