Disclaimer 1: This is my understanding, if you spot something wrong, please assume best intentions and let me know, thanks!
Disclaimer 2: All uses of the word male/men/female/women here are subject to the caveats I’ve tried to detail below.

I had to write this post as the topic of sex and gender (in sports) has popped up yet again this Olympics :)

Firstly, sex and gender are not the same. A person’s sex can be male or female, and so can a person’s gender, and that is where the confusion may arise. Let’s dive in.

Sex

Sex refers to what a person is. Is a person male? Is a person female? Or are they neither (or both)? And how do you tell? Is the distinction even important, and if so, why?

Let’s begin with why we need to make a distinction. At least when it comes to sports, men have a clear physical advantage in many sports. To take one example, the world record winner for the women’s 100m, wouldn’t make the finals on the men’s side. If there wasn’t a separate category for women, many of the top prizes in sports would be exclusively contested by men.

With that out of the way, let’s move on to “how can you tell?” The most common answers you may get to identify a man may be to see how they look. Do they look manly? That, of course, fails, because men may (to varying degrees) look “feminine”, and similarly, women may look “masculine”. As the sex verification in sports wiki article details, this has undergone various iterations - from gynaecological exams to chromosomal testing to hormone testing. Even when you think “science” may provide a clear-cut answer (“a person with a Y chromosome is male”), it isn’t always as simple:

a central contention was whether a Y chromosome yields a competitive advantage because it is not always accompanied by “manly” attributes that provide greater strength, power, or flexibility

In addition, you can pass one test, but not the other (i.e. you may have the Y chromosome but female gonads or vice versa). This only applies to a small portion of the population, but importantly, this has happened to multiple Olympic athletes. Now, we have a conundrum - do we exclude this population from participating in female events (because they may have an advantage)? They can’t take part in male events as the top male athletes are significantly superior physically.

The latest iteration involves hormone testing, where a person’s testosterone levels are checked, and if too high, they are put on suppressants. This creates another interesting dilemma - all sports likely have genetic differences that convey superiority, which makes for a better athlete. Phelps’ wingspan, for example, is larger than the average man’s (in relation to his height). Do we ask Phelps to somehow artificially shorten his wingspan? Do we create a separate event for him? Most prominently, Caster Semenya was affected by multiple bans (and unbans) as a result of attempts to determine the “right” way to go about this. Dutee Chand was another athlete (of many) similarly affected). They are all intersex.

Gender

Now, the other half of the coin. Gender is what someone identifies as, and has been a hot, contentious political (for some reason) topic in the 2010s. Gender is who you think you are. While most men (for some definition of men) see themselves as men and most women see themselves as women, some don’t. And even those who do, may see themselves as “masculine” only to some degree. For example, if you identify people with big beards, a love for cars & motorbikes, who drink alcohol and love sports as “real” men, many men won’t fit in that category. Likewise, if women all have to love fashion, makeup and gossip (forgive me for going with stereotypes, but I’m trying to make a point here), then most women won’t identify themselves along those lines. This is where the idea that “gender is a spectrum” comes in. You do have men who love fast cars, beer and heavy metal, but you also have men who like fashion, clean-shaven and are shy. This isn’t a recent phenomenon either, as you may have heard of tomboys and I distinctly remember the term “metrosexual” being thrown around in the 90s/00s. Note: this does not mean these people are gay or lesbians (which is another topic altogether). This is also why people say gender is a social construct. Biologically, nothing seems to draw men towards cars or sports. It’s a determination by society.

Given that gender lies on a spectrum, there may be people who identify as a gender different from their sex (assigned at birth). In the past, there have been attempts to “remedy” this by trying to change people’s brains (BAD IDEA), which resulted in lobotomies and deaths. Then, as humanity realized this was the completely wrong approach, they have moved towards allowing people to change their bodies to map more closely to their mind. These people are trans - meaning they identify as a gender different from the sex assigned to them at birth. Now, for trans people, there is a different controversy surrounding their participation in sports. Most famously, Lia Thomas was in the news, after which the International Swimming Federation (FINA) banned transgender athletes from participating in women’s sports (some exceptions apply). This is a different but still complicated issue. The argument from those who support the ban generally goes like, “they were men, and so they retain the physical advantages men have”. The opposing argument is along the lines of “taking hormone blockers removes any advantages they may have had”. This is further complicated by whether the person in question went through male puberty or not. Importantly, this is not the same as intersex people mentioned above.

Lately, some people have chose to identify as neither male/female (and doing away with all the social baggage that comes with it). They are “non-binary” (i.e. they identify as neither male nor female) or “queer” (this term was earlier used to refer to gays as well).

If all this is confusing and strange to you, think of analogous ideas. Think of religion X. You may be “born a X” (technically born into a X family), but not identify as a X. Growing up, you just don’t get it, and everything seems to be a fight and a struggle (i.e. what you see around you doesn’t jive with what you think/feel), until one day you realize you don’t “have to” be a X. You can just identify as “not X”. Or maybe your countrymen are supposed to be good at math, and you are not. It may be easier to accept that in reality, math skills lie on a spectrum among your countrymen, and you can simply identify as one not good at math.

Sexual orientation

A totally different topic is sexual orientation, i.e., “which sex (gender) are you attracted to?”. This is where the terms homosexuals (gays, lesbians), bisexuals, pansexuals, asexuals all fit in for the purposes of discussion. I’m guessing the confusion arises because of the LGBTQ acronym (where the first three letters fit in this section, but “TQ” - for Transgender and Queer - does not). If you’ve heard of the LGBTQIA acronym, the “I” stands for Intersex (under the “Sex” section), and the “A” stands for Asexual (under the “Gender” section).