How Many Times…

Have you seen comments about our chromosomes, if you have XY you’re male but that is nineteen fifties thinking.

This popped up on Facebook…

Sex biology redefined: Genes don’t indicate binary sexes
Stanford Medicine
Author Andrea Ford
Published on February 24, 2015

Imagine being a forty-six-year-old woman pregnant with her third child, whose amniocentesis follow-up shows that half her cells carry male chromosomes. Or a seventy-year-old father of three who learns during a hernia repair that he has a uterus. A recent news feature in Nature mentioned these cases as it elaborated on the spectrum of sex biology. People can be sexed in a non-straightforward way and not even be aware of it; in fact, most probably aren't. As many as 1 person in 100 has some form of "DSD," a difference/disorder of sex development.

The simple scenario many of us learned in school is that two X chromosomes make someone female, and an X and a Y chromosome make someone male. These are simplistic ways of thinking about what is scientifically very complex. Anatomy, hormones, cells, and chromosomes (not to mention personal identity convictions) are actually not usually aligned with one binary classification.
[…]
As quoted in the article, Eric Vilain, MD, PhD, director of the Center for Gender-Based Biology at UCLA, explains that sex determination is a contest between two opposing networks of gene activity. Changes in the activity or amounts of molecules in the networks can sway the embryo towards or away from the sex seemingly spelled out by the chromosomes. “It has been, in a sense, a philosophical change in our way of looking at sex; that it's a balance.”

What's more, studies in mice are showing that the balance of sex manifestation can be shifted even after birth; in fact, it is something actively maintained during the mouse's whole life.

Mother Nature does not like simple, life is so complicated and there’re many facets that we do not understand. It is like an onion, when we find something there are always another layer beneath that layer.

As our understanding of biology continues to advance, our social, legal, and medical systems will have to evolve as well. Check out the Nature feature for a discussion of these problems, as well as more interesting research into the biology of sex.