Hermaphroditus, the Greek god with bisexual attributes, was the son-daughter of Hermes, the god of athletics, secrets, and occult philosophy, and Aphrodite, the goddess of love. The bisexual theme was immortalized in countless statues by the Greeks and Romans, depicting a normal woman with normal male external genitalia (not a combination commonly encountered in real life). Pliny (23-79 A.D.) was the first to apply the term hermaphrodite to humans, presenting a description in his massive work, Historia Naturalis.

Abnormal sexual differentiation can occur as a result of a mixture of gonadal sex (true hermaphroditism) or complete uncertainty of gonadal sex (gonadal dysgenesis with some virilization). A true hermaphrodite possesses both ovarian and testicular tissue.

Both types may be contained in one gonad (ovotestis) or less often, one side may be an ovary, the other a testis. The internal structures correspond to the adjacent gonad. In the majority, external genitalia are ambiguous with sufficient male character to allittle male sex assignment. However, three-fourths develop gynecomastia and half menstruate after puberty. Sixty percent are genetic females (XX), several are XY, the rest are mosaics with at least one cell line XX. 46,XX individuals without SRY may have a mutation of an autosomal gene that permits testicular determination in the absence of the testis determining factor.