Human hermaphrodites are extremely rare.
Pseudohermaphrodites have the internal sex organs of one sex, but the
external appearance of the other. The true sex of the latter becomes
apparent at adolescence when the normal hormone activity appropriate to the
internal organs begins to function. Human pseudohermaphrodites show
functional disturbance of the endocrine glands, especially of the pituitary
or adrenal glands, and do not possess two sets of functioning sex organs.
Because of the homology between male and female sex organs, it may be
difficult to tell whether a human hermaphrodite is a female with
overdeveloped clitoris or a male with underdeveloped p***s, cleft scrotum,
and nondescendant testes. Recently, many persons have undergone surgical or
hormone treatment to modify their nonfunctioning sex characteristics and
emphasize the sex indicated by those that are functional.
This answer is a composite from two sources:
The Hutchinson Family Encyclopedia, Helicon Publishing Ltd 2000
Funk & Wagnalls Encyclopedia as provided on the InfoPedia CD-ROM