Black or white, good or bad, right or wrong, light or dark, leave or remain, man or woman: our whole world is split in two. Is this a consequence of evolution giving us bi-fold symmetry, left versus right? Or is it more fundamental?

It’s undeniable that binary thinking dominates discourse. We argue for and against, a claim is true or false, a stranger could be friend or foe. There are two sides to every story, or so we say. It takes two to tango. Two is the magic number, embodied in either/or language. We don’t stop to wonder why, to question this apparent need to see things in terms of us or them.

Nowhere is this more apparent to me than when people are arguing about people: about human traits. Neurodivergent or neurotypical, autistic or allistic, gay or straight, female or male. That last one especially is something I’m attuned to as a transgender woman: the hoops some will jump through in an attempt to draw a line between women like me and other women have to be seen to be believed.

Appeals to science don’t work because like a lot of things in the real world–as opposed to the simplified models we use to explain them–human biology is fuzzy at the edges. And gender isn’t simply biology in any case, not by a long chalk. My own mother didn’t give birth to me but was no less a mother for that: motherhood cannot be reduced to childbirth.

Rather, her motherhood was established by the sum of what she did in raising me and how she was seen by everybody around her. This is what is meant when people talk about a “social construct”: this concept of motherhood based on something other than purely objective measurement. There is no set of hard and fast rules defining who can be deemed a mother.

Yes, most come to it through giving birth but not all, and my mum’s motherhood is no less valid. And by the same token, trans women’s journey to womanhood might be different from most other women’s but that’s no reason to reject us. My experiences are not yours. My life is different from that of my mother, as hers was different in turn from her mother’s. My daughter will make her own path and not tread slavishly in my footsteps. Four different women, four different lives and experiences. But four women nonetheless.