quote:

---

Gender, often said to depend solely upon anatomy or hormones, may depend also on hard-wired genetics, according to new research that could help doctors and lawyers better understand the one in 4,000 babies born with both male and female traits.

"The biology of gender is far more complicated than XX or XY chromosomes and may rely more on the brain's very early development than we ever imagined," researcher Eric Vilain, M.D., reported today at the American Association for the Advancement of Science (AAAS) Annual Meeting in Washington, D.C. "Surgical sex assignment of newborns with no capacity to consent should never be performed for cosmetic reasons, in my opinion," said Vilain.

---

More from original source, Science Daily...

quote:

---

Through his clinical work with some 100 patients, Reiner said, those who are genetically male, with the 46 XY makeup, will tend to identify themselves as boys if they can react and respond to male hormone, and even if they are born without a penis, underwent surgical reassignment and were raised as girls. "These children know who they are," Reiner said. "It's encouraging that many more surgeons today are choosing to postpone surgical gender assignment until the patient is mature enough to take that step. Of course, social and legal gender assignment still must be carried out at birth."

Scientific evidence on gender is revealing an increasingly complex picture. For example, conventional wisdom has held that gonadal hormones dictate whether the brain becomes masculine or feminine during development.

But, even before hormonal influence, Vilain has reported, embryonic mouse brains show clear gender-specific differences. Building on his previous discovery, Vilain said, he and colleagues have since identified 54 genes that were differentially expressed in the brains of male and female embryonic mice just 10 days after conception, prior to hormonal exposure.

"Differences of gene expression between male and female brains, very early on, suggest that our brains may be hard-wired at a very early stage to become male or female," according to Vilain.

---

[ 28 February 2005: Message edited by: Hephaestion ]