True hermaphroditism

In ovotesticular syndrome, XX is the most common (55-80% of cases); most individuals with this form are SRY negative.[8]

Next most common are XX/XY (20-30% of cases) and XY (5-15% of cases), with the remainder being a variety of other chromosomal anomalies and mosaicisms.[9][8]

Some degree of mosaicism is present in about 25%.[8]

Encountered karyotypes include 46XX/46XY, or 46XX/47XXY or XX & XY with SRY mutations, mixed chromosomal anomalies or hormone deficiency/excess disorders, 47XXY.

Less than 1% have XX/XY chimerism.[8]

There are extremely rare cases of fertility in "truly hermaphroditic" humans.[15][17]

In 1994 a study on 283 cases found 21 pregnancies from 10 true hermaphrodites, while one allegedly fathered a child.[15]

As of 2010, there have been at least 11 reported cases of fertility in true hermaphrodite humans in the scientific literature,[4] with one case of a person with XY-predominant (96%) mosaic giving birth.[18] All known offspring have been male.[19] There has been at least one case of an individual being fertile as a male.[16]

There is a hypothetical scenario, in which it could be possible for a human to self-fertilize. If a human chimera is formed from a male and female zygote fusing into a single embryo, giving an individual functional gonadal tissue of both types, such self-fertilization is feasible. Indeed, it is known to occur in non-human species where hermaphroditic animals are common.[20] However, no such case of functional self-fertilization or true bisexuality has been documented in humans.[14][10]

The U.S. legal case of M.C. v. Aaronson, advanced by intersex civil society organization interACT with the Southern Poverty Law Center, was brought before the courts in 2013.[26][27][28][29] The child in the case was born in December 2004 with ovotestes, initially determined as male, but subsequently assigned female and placed in the care of South Carolina Department of Social Services in February 2005.[30] Physicians responsible for M.C. initially concluded that surgery was not urgent or necessary and M.C. had potential to identify as male or female, but, in April 2006, M.C. was subjected to feminizing medical interventions.[30] Bear in mind that "The reconstruction of female genitalia was more readily performed than the reconstruction of male genitalia, so ambiguous individuals often were made to be female."[31] He was adopted in December 2006. Aged 8 at the time the case was taken, he now identifies as male. The Southern Poverty Law Center stated that "In M.C.'s condition, there is no way to tell whether the child will ultimately identify as a boy or a girl. Instead, the doctors decided to assign M.C. female and change his body to fit their stereotype of how a girl should look."[27][32] The defendant in the case, Dr. Ian Aaronson, had written in 2001 that "feminizing genitoplasty on an infant who might eventually identify herself as a boy would be catastrophic".[33][30]

The defendants sought to dismiss the case and seek a defense of qualified immunity, but these were denied by the District Court for the District of South Carolina. In January 2015, the Court of Appeals for the Fourth Circuit reversed this decision and dismissed the complaint, stating that, it did not "mean to diminish the severe harm that M.C. claims to have suffered" but that in 2006 it was not clear that there was precedent that the surgery on a sixteen-month-old violated an established constitutional right.[34] The Court did not rule on whether or not the surgery violated M.C.'s constitutional rights.[35]

State suits were subsequently filed.[34] In July 2017, it was reported that the case had been settled out of court by the Medical University of South Carolina for $440,000. The university denied negligence, but agreed to a "compromise" settlement to avoid "costs of litigation."[36]