Here's what we do know: If you ask experts at medical centers how often a child is born so noticeably atypical in terms of genitalia that a specialist in sex differentiation is called in, the number comes out to about 1 in 1500 to 1 in 2000 births.  So, worldwide there are millions of people who are intersex.  They are assigned a "sex" at birth which may be wrong and often given surgery as babies to make them conform to that sex assignment.  Sexual identity is not binary...get over it...use a private stall if you can't deal with not knowing what sex the person next to you is assigned.