FFS. Again, it's that mixing up and mashing up between sex and gender.
It's not at all difficult, really, is it? That difference between sex and gender?
Gender - social construct, varying across different times and locations and societies. If gender is important to you, then have at it. Have whatever genders you fancy. Fill yer boots.
Sex, on the other hand: sex is your physical body, your biology. In the vast, vast majority of people, sex is observed at birth, because it's absolutely bleedin' obvious. Humans are dimorphic. In order to reproduce, a female gamete and a male gamete must meet and join. Female gametes are produced by women, and male gametes are produced by men.
Gender: social construct, details vary between various societies in various locations and at various times. Mutable.
Sex: fact of biology. Immutable, regardless of society, location or era.
And I'm an arts graduate...