There are increasingly more cases in which the inner sexual feelings do not match the external genitalia. And it's not merely about sexual orientation. There are also numerous cases of ambiguous genitalia in humans, about 1: 4500 births.

New discoveries are again underlining the fact that men have an XY pair of sex chromosomes, while women an XX one. Many genes can overcome this arrangement and turn XX individuals into men and XY carriers into females. It appears that sex is under the control of a fragile balance between about (till now found) 50 promale, antimale, and profemale genes.

The body's reaction to testosterone prevails over the presence of the Y chromosome in deciding the sex of the future individual. Androgens (testosterone being the most important) are believed to model the male's sexual development throughout life, with the peak during puberty. But complete androgen insensitivity syndrome (CAIS), with a rate of 1 in 20,000 people, produces normal females that genetically are males, having XY sex chromosomes, but almost always identify as women. It is due to mutations in the gene encoding for the androgen receptor; these individuals are immune to the effect of testosterone.

A new research shows that these women can function perfectly with their body, without the need of vaginal surgery. The team at the Johns Hopkins Children's Center pointed out at the American Academy of Pediatrics Conference Oct. 26 through Oct. 30 in San Francisco that vaginal reconstruction should be the decision of most teens or adult women born with any kind of inter-sex condition (hermaphroditism), characterized by the presence of both female and male genitalia.

CAIS women are born with relatively shallow vaginas, requiring or not repairing surgery and undescended testicles that must be removed. The team warns that vaginal surgery should be effectuated after puberty, when the woman has finished her physical development and has the maturity to make the right choice.

"It is a common misconception in the general public - and quite often among doctors - that most girls born with this condition should have vaginal reconstruction in order to be sexually active. Our findings show that, on the contrary, most young women choose not to have the surgery, have vaginal depths that are within normal parameters and can lead active sexual lives.", said lead researcher Dr. Todd Purves, a urologist at Hopkins Children's.

From 29 CAIS women, 38 % had undergone vaginal operation. The team found that 80 % of those who did not have operation had an active sexual life, compared to 70 % of those who did. "As surgeons, we need to make sure that the parents of babies with this disorder understand that their daughter may not even need vaginal surgery, and if she does, it is a decision that should wait until after adolescence", Purves said.