Amid all the recent Skeptics related flap about sex and gender, one thing has stood out to me. It is the assertion that people's 'biological sex' is obvious because of chromosomes. This is a dubious statement for many reasons, but prominent among them is this: of the numerous people I have questioned after they made this statement, all of whom have described themselves with confidence as either male or female, not one has been able to tell me with certainty what their own chromosomes look like.
Let's think about that for a minute.
Considering this, one friend told me that he'd be prepared to make a bet. I respect that position - it's not hard to guess the likely outcome - but it misses the point. The argument that sex is obvious because of chromosomes implies that we are looking at chromosomes and then deciding what sex somebody is (generally referred to as 'gendering' them).
This is patently not what we are doing. We are, as a rule looking at secondary sex characteristics or aspects of presentation (or, in the case of babies, genitals) and deciding, on that basis, what sex category to place people in; then, on that basis, we are making an assumption about what their chromosomes are likely to look like.
Ergo, unless the first we see of someone is a cell under a microscope, chromosomes play no role in what is 'obvious'. They may play a role in confirming or contradicting that later on, but it's rare.
Perhaps what is intended here is the advancement of the idea that sex can always be clarified by chromosomes. This relies on a very dogmatic view of sex in a context where scientists and doctors are far from reaching a consensus (sex can be defined by a number of characteristics that don't always neatly line up), it runs into problems when it comes to individuals with variant sex chromosomes (not super rare) and it plainly doesn't fit with our social reality.
When we look at someone's chromosomes, we may well find that they're not what we expect. Some kinds of intersex people have bodies that look completely male or female whilst their chromosomes might lead you to expect the opposite; to claim that they are 'really' gendered by their chromosomes is to dismiss at a stroke their whole life history. Not only does this render the notion of sex pretty much meaningless (lots of us don't reproduce anyway* but sex has a huge effect on how we interact), but any competent biologist will tell you that genotype does not equal phenotype, for a host of reasons, and phenotype is no less biologically 'real'.
Although many intersex people are identified at birth, many don't find out until much later in life (it's reasonable to suppose that a fair number never know at all). Every now and then a story hits the papers, usually with a lurid headline. A fifty year old man has found out he's really a woman! they tell us, except of course he has done no such thing. If he has always felt comfortable with his male identity, with a body that looks the way it does, he's not likely to change that because of a curious medical detail. His family, friends and workmates may raise eyebrows at the unexpected news but they won't suddenly see him differently. He'll still just be this guy, you know?
If you are minded to dismiss somebody as not 'really' male or female because their chromosomes don't match their appearance, you had better (a) actually know what their chromosomes are instead of basing bullying on a guess, and (b) give serious thought to how you would feel and behave if you discovered your chromosomes were not what you expected. Would you really change your lifestyle completely? Would you start thinking of the life you had lived as false, of yourself as fake? Are chromosomes that important to you?
There is a parallel here with many people's approach to sexual orientation. I have had many conversations with men who tell me they would never feel attracted to a man (by which they usually mean a male-bodied person; and so on, for other categories of sex and orientation). Not wouldn't want to sleep with, which is entirely their prerogative, but wouldn't feel attracted to. I find this odd because when I first notice somebody appealing I'm not usually looking at their genitals or peering at their chromosomes under a microscope. YMMV. I usually notice things like their curves, their (ahem) secondary sexual characteristics, and how they move. Despite my many years of living and working in trans and intersex circles, I have no magical power to perceive either the private anatomy or the gender identity of a fully clothed stranger. Simply considering the statistics, I'm sure I must have been attracted to some people where one of both of those things in fact defied my expectations.** Attraction is not a thing we control and, in most contexts, it's really not a thing we need to worry about that much. After all, we cope with other instances where otherwise cute people turn out to have characteristics that are deal breakers (for instance, I know a fair few people who refuse to sleep with folk who vote Tory, and they don't break down in tears if they discover they've accidentally lusted over one).
Sex, gender and sexual orientation are complicated things. Unless we're monitoring discrimination or planning to get intimate with someone then they are also, as a rule, none of our business. We don't need to impose dubious scientific definitions on them or get our knickers in a twist trying to reconcile the inherent fuzziness of
biology with a compulsion to neatly index everything. There is variety everywhere in nature - without it, evolution wouldn't work - and any truly scientific approach must acknowledge that. So in the end, it doesn't hurt science to respect people's lived experiences. In this situation at least, there need be no conflict between good science and good manners.
* One definition of sex used in biology holds that females are those individuals in a species who produce larger gametes than other members (males). It would work fairly well except that a significant percentage of individuals in most species, including humans, don't produce any gametes.
**This isn't to suggest that cross dressers set out to deceive people. I start from the assumption that, like me (when not in professional wear) they dress to please themselves, not because they're sleazily determined to seduce me. Others might want to give this approach a try.