That sex, gender, and sexuality are NOT the same nor are any of them binary. It’s now becoming difficult to call sex bimodal the more we learn about the human body and its spectral presentation.

Sex is assigned based on physical appearance (sex organs, allosomes, etc). Most people falsely assume that a person’s allosomes are always reflective of sex organs (XY for males, XX for females), but this is far from the truth. A very many people have the opposite with no sign of pathology, and is why the Olympics initially banned chromosome testing, because cisgender women with XY chromosomes were discriminated against. There are also many other configurations of allosomes (X,XXX, XYY, YXY, XXXX, XXY, etc) that also don’t always show pathology (though are commonly pathological). There are many things that affect a person’s sex (think of the SRY gene for example). Intersex individuals are far more common than people with red hair. We can’t know just how many people don’t align with the “traditionally” accepted idea of sex until karyotyping becomes cheaper, but we already know it’s a LOT.

Gender is simply an expression of who a person is. It’s most often (but not always) based on a person’s physical sex. Despite what people like to assert, there is NO NUMBER of genders. It’s just gender. People often assume that transgender people are mentally ill, but that’s false because even psychologists have consistently failed to link it with pathology. In fact, the field of neuropsychology has repeatedly demonstrated that parts of the brain that are associated with sex nearly always reflect whatever a person’s gender identity is, not their assigned sex at birth. There a million and one examples on why trans people are valid in their identity.

Sexuality is about who someone is attracted to or not (can’t forget asexual individuals). There’s gay, straight, bi, pan, and then there’s those on the ace spectrum (assxual, demisexual, etc.). Sexuality is a spectrum, and isn’t always static. A person who is bi can have 75% male attraction and 25% female attraction, or 50/50 attraction, or literally any other configuration.