(Note: I have been contacted by several people and informed that this piece appropriates intersex isssues to promote trans issues. I apologize profusely, and that was never my intent. I wanted to make it clear that biology does not support a sex/gender binary, and promote acceptance of all outside that binary. Focusing on a single group, transgender, outside that binary, was an error borne of frustration with current attacks resulting from prominence of trans individuals currently in the news. Again, I apologize for conflating the two issues, and would like to be clear that I — and biology — support treating all people as people, regardless of gender identity.)
If you have internet service or television, or have stood in a grocery store line, you may be aware that transgender people have been a bit more visible lately. Maybe you saw Laverne Cox or Janet Mock in an interview, or you’ve seen memes on Facebook about Caitlyn Jenner (formerly known as Bruce Jenner). You may have seen any of these ladies on a magazine cover. You may have seen less famous transgender women in sadder news stories — like teenager Leelah Alcorn’s suicide.
Something else you may have noticed, particularly if you like comment sections, is that when the topic of being transgender (sometimes this also applies with someone being gay, bi, asexual, or otherwise non-cis) comes up, somebody always smugly references biology. To this person, there are obviously two genders: one with the genotype XY, phenotype male, and one with genotype XX, phenotype female. To this person, biology is a trump card: you can’t change your DNA, so Caitlyn Jenner is a man.
(If high school biology is a squeamishly distant memory, genotype is basically the actual genetic code, and phenotype is how it presents — that is, the outward appearance. It’s a bit more complex than that, but that’s enough to understand the general idea.)
You have likely never seen anyone respond, though, to say, “But we know there are more than two genotypes.” Actually though, we do. There are. Some people have 3 X chromosomes, and some have XXY as a genotype. It’s also possible to have a partial third sex chromosome.
There are quite a few phenotypes that can result from this. An intersex person (you may be more familiar with the word ‘hermaphrodite’ — it’s not the accepted term, but you’re more likely to have encountered it in a dirty joke) is one of them (though an intersex individual may also present with a ‘normal’ XX or XY genotype). Intersex refers to a person whose genitals and sexual organs aren’t exactly what we’ve defined as one gender or the other — if you’re referencing old dirty jokes, you know this as a person with the genitals of both sexes. Yet again, it’s quite a bit more complex, including essentially anything outside the ‘binary’ phenotypes of genitalia.
(Note: Again, I don’t intend to conflate intersex and transgender — both are outside the gender binary that many insist exists, but are two distinct groups with their own issues. Both deserve recognition and acceptance on their own grounds.)
Intersex isn’t the only possible phenotype for genotypes outside the XX and XY binary, though. A person with one of these genotypes may have a number of other phenotypes, including the outward appearance of one sex, but hormones not quite matching up to it. (The U.S. Library of Medicine has a lot more on this, but in short, you need to understand that humans do have more than two genotypes and phenotypes.)
(A person may also have more than one genotype, thanks to two distinct conditions known as chimeraism and mosaicism, but again, we’re keeping simple. If you want to dig deeper into those, check Gene Geek.)
Now, when you say, “DNA can’t be changed! If you were born a man, you’re always a man!” you aren’t really judging that person’s gender based on his or her DNA — you’re basing it on outward appearance — likely secondary sex characteristics, like an adam’s apple, facial hair, or breasts. You probably aren’t judging based on primary sex characteristics — such as genitals and reproductve organs. Even if you are, though, you’re still looking at the phenotype, not the genotype.
Now, let’s take this apart a bit: basically, you are saying, I see breasts, therefore I know that this person’s genotype is XX, and she is female. Remember when I said it’s more complex than that? It is. After all, Caitlyn Jenner has breasts, but her genotype hasn’t changed. Or, you’re saying, I know this person was born with a penis, therefore he is male. However, you do not know his (or her) genotype. You are assuming that this person has the XY genotype, because of what you assume you know about his or her genitals.
The appearance of breasts (including without cosmetic surgery) doesn’t mean an XX genotype. The appearance of an adam’s apple does not mean an XY genotype. Those are certainly the most common, and what we call ‘normal,’ but remember: genetics are more complex than what you can see.
You are right, though: we can’t (in general, with current knowledge available to us) change someones chromosomes in order to make them a different biological sex. Where you’re wrong is in assuming that you know a person’s biological sex. You don’t. You know what you see and what you’ve been told and maybe which bathroom this person used to go into.
We know there are more than two genotypes for sex. What we need to come around to, as a society, is recognizing that the two phenotypes we have defined as ‘male’ and ‘female’ don’t fully reflect our genome. (We also know that gender is more complex than sex, but we’ll try to keep it simple for the moment.)
Do we know the genome, or choose to speculate on the genome, of Leelah Alcorn, Laverne Cox, or any of the other transgender people who have made big headlines?
Nope. Other people’s genitals aren’t your business — and neither are their genes. Knowing that there are more than two genotypes for sex is important. Knowing what another person’s genotype is, is not important.
Do we have evidence that transgender people have a different genome, and that a transgender woman might have been born with a set of sex chromosomes that cause her to be more genetically similar to a female, but to present with the appearance we’ve defined as male?
Well, actually, New Scientist reported years ago that studies showed differences in brain scans between transgender and cisgender people. Transas City also reports that we can see some links between less-common sex chromosome sets and being transgender.
But do we have an absolute, oh, here’s the transgender gene, that’s the transgender genotype, a person with this set of genes is transgender and a person without it isn’t?
We’re still learning, though.
What we do know is that if you are stomping your foot and insisting that XX is woman and XY is man and that’s the entire scope of human sexes, you’re flatly, undeniably, demonstrably wrong.
We also know that if you’re using that as an excuse to discriminate against transgender people, you’re either going to have to stop…or find a different excuse. Ideally, stop discriminating, because really, that’s just nicer for everyone all around anyway.