Answer: Intersex condition
This condition is genetic for the body's cells are unable to respond to androgen, or "male" hormones. They usually have an Androgen Insensitivity Syndrome where the fetus is exposed to unusual levels of sex hormones however, some individuals have partial androgen insensitivity.
Moreover, these intersex individuals don't have to search for evidence that they are inter-sexed, the evidence is in their own bodies for they may be born with unusual combinations of male and female chromosomes, hormones, and anatomy.