Affected individuals have sex chromosomes showing male-female mosaicism (where one individual possesses both the male XY and female XX chromosome pairs).
The ovarian and testicular tissue may be separate, or the two may be combined in what is called an ovotestis.
She is also an activist for intersex people -- (formerly known as hermaphrodites) Her memoir "Mighty Hermaphrodite" will be published next spring.
Intersex people (formerly known as hermaphrodites) are those born with bodies that are difficult to classify as either "male" or "female." Since results of Semenya's tests were apparently leaked, it seems that her body doesn't conform to the definition of "female" as one who has ovaries.
However, intersex surgery has long-term consequences for affected individuals.
Later in life, for example, the person may not be satisfied with the results of surgery and may not identify with the assigned gender.
Individuals with a 46, XX chromosome complement usually have ambiguous external genitalia with a sizable phallus and are therefore often reared as males.