Problem:

Hijra are people who have a penis (not sure if sexually active) but look much like a female (perhaps for some feminine biological property). Wikipedia says they are "physiological males who have feminine gender identity"
Also, I just came to know there are some more types of third gender people.
Now, is there really any BIOLOGICAL third gender which cannot be categorized as male or female? Or its always possible to categorize them to male or female?

"physiological males who have feminine gender identity" explain it.