What do we really know about human sexuality anyway? Masters and Johnson, Alfred Kinsey and legions of less-famous scientists have devoted cumulative centuries of work around this topic. For some questions there are pretty solid answers, and for others there are more questions. Some of the work has not been free of political, religious or other motivations besides pure scientific inquiry, so one always has to read carefully. I present here a decidedly non-expert review of some of the pertinent questions and answers I found useful.

4 Different Spectra
Let’s start with a theoretical framework based on the idea that in nature, many species show a normal diversity within species, across many characteristics.. You can arrange the individuals on a spectrum (nose: Barbra Streisand to Mia Farrow; hieght: Willy Shoemaker to Walt Chamberlain, etc.) Why not also gender? Most humans have chromosome and hormonal mixes that put them pretty close to the “male” or “female” ends of the gender spectrum, but there are more people in between – intersex – than you might think.

Biological sex:
Male Intersex Female

How common is it to be not completely male or female? The Intersex National Association (?) website notes, “Here’s what we do know: If you ask experts at medical centers how often a child is born so noticeably atypical in terms of genitalia that a specialist in sex differentiation is called in, the number comes to about 1 in 1,500 to 2,000 births. But a lot more people than that are born with subtler forms of sex anatomy variations, some of which won’t show up until later in life.” A review of medical literature from 1955 to 1998 estimated that as many as 2 in 100 babies had some difference, in body organs, XY chromosomes, and/or hormonal patterns from ‘standard male or female.’ (Blackless, M et al “How Sexually Dimorphic Are We? Review and Synthesis,” American Journal of Human Biology, 12, Page(s): 151-166, 2000. or http://transgenderinfo.be/wp-content/uploads/2013/01/Blackless-How-Dimorphic-2000.pdf%5D

1% is a pretty small minority, but in the context of normal biodiversity it compares to other ‘natural’ differences among humans. For example, humans are born with 1 of 4 ABO blood types: A, B, O (neither A nor B) and AB (both). and either positive or negative for Rhesus factor, meaning everyone has one of 8 types. People who are B- are only 0.6% of the US population; these folks present a matching challenge to hospitals when they need transfusions, but we don’t consider them freakish.

Gender Identity: what you believe deep down that you are
male neither/third gender Female

Most people’s belief about their gender matches, conveniently, their biological sex, but for some number there is a mismatch. This is called by some psychologists Gender Identity Disorder. People who change the gender they present to the world to match what they feel about themselves are transgender. (This might or might not include surgery.) How common is this? The Transgender Youth Family Alliance estimates about 1 in 500; a study in the Netherlands found it to be 20 times more rare. (Malpas J, “Between Pink & Blue,” in Family Process Vol 50, #4 2011]

A third spectrum is gender expression, a pattern of behaviors that typically “belong” to males or females in your society. It is heavily, if not altogether, culturally defined, and often situationally specific. Acting aggressively and speaking confrontationally in some circumstances may be “unfeminine,” but in a context of threat to her children might be “normal mama” behavior. You can see that studying the incidence of this gets very squishy very fast. In recent decades, the blurring of strict gender roles has made this spectrum more open for everybody, if perhaps more for women than men.

Gender expression: appearance and behavior patterns
“Feminine” androgynous “Masculine”

How separate are these spectra? Just because you are in the middle of one might have no bearing on where you are on the others. People in the middle of any of these are certainly in a minority, and in some settings at risk of bullying or hate behaviors. Middle positions on these spectra, or positions opposite the biological sex position can be difficult places to be in and of themselves, but many of the complications come from assumptions others make about sexual orientation. But that is the fourth, and separate spectrum.

Sexual orientation: to whom are you sexually attracted?
Attracted to Men both (bisexual) Attracted to Women
or neither (asexual)

How common is non-heterosexuality? A 13-site study of high school students over nine years by the Centers for Disease Control found varying rates of reported sexual orientations. The % who identified as gay or lesbian ranged from 1 to 2.6%, 2.9 − 5.2% bisexual, and 1.3 − 4.7% unsure. A Gallup phone survey during the summer of 2012, believed the largest to investigate sexual orientation and gender identity, found that 3.4% of American adults identify as lesbian, gay, bisexual, or transgender. [Gates, Gary J and Fran Newport , “Special Report: 3.4% of Adults Identify As LGBT” 10/18/12]

So, given that so many people fall on the outer ends of all these spectra, and the majority of those line up always on the left end or right end, whichever spectrum you choose, is it lazy or convenient to combine them? In other words, can a parent draw any conclusion from gender-atypical behavior in a 3-year-old? A 12-year-old? A 21-year-old? Many (but far from all) lesbian, gay and bisexual people have shown some “atypical gender expression” as children. Their dress-up play and favorite playmates were of the other gender, their favorite colors caused alarm in grandparents, etc. Almost all transgender people had frequent gender expression to match their convictions about their gender, starting from a very young age and quite consistent over the years. But is gender-nonconforming behavior in children strongly predictive of anything on other spectra? Not especially. 5-13% of boys and 20-26% of girls reported their own behavior as sometimes cross-gender; significant subsets reported sometimes wanting to be a different gender. [Achenbach T M & Edelbrock C, “Manual for the Youth Self-Report and Profile.” Burlington VT : U of VT Dept for Psychiatry; 1987, as reported by Meyer III WJ in his commentary in “Pediatrics Vol 129 #3” March 2012, p 571] These rates are far higher than the rates of biologically intersex and transgender people, and somewhat higher than estimates of non-heterosexuality.