These days - now that we can sex a child when it is still the size and consistency of an avocado - birth is less of a player in the gender games. But that only entrenches the genderisation process. By birth, many a child's gender is fully fitted, colour-coded and ready to wear. This has always seemed to me a simple descriptive act, cultural clothing for nature's given form. But what if that's wrong? What if the garment is actually a mould? Behaviourists have argued ''nurture'' for a century and, clearly, the meaning of ''boy'' or ''girl'' is partly cultural. But what if the distinction itself is illusory? If the birth or pre-birth genderising is actually more creative than descriptive? Norrie, born a boy, underwent (what was then called) sex-change surgery before deciding womanhood wasn't for hir either. This began the long battle for official recognition as being of ''non-specific'' gender. As Justice Beazley found: ''The word 'sex' … does not bear a binary meaning of 'male' or 'female' … There are other sexual identifications that may be registered.'' On the face of it, this decision simply puts a third box on the birth form, as already exists for passports, validating the small group of people who are born neither male nor female. This is good - but the ripples are far broader and more interesting.

The court didn't just recognise Norrie's right to gender-neutrality. It also accepted that the determinants are part-psychological. Norrie is ungendered because that's how zie feels. Justice Beazley quoted a 1993 case: ''Sex is not merely a matter of chromosomes … [but] also partly a psychological question (a question of self perception) and partly a social question (how society perceives the individual).'' Add to this the vast array of hermaphroditic, intersexual, non-sexual and transsexual possibilities and the fact that ''male'' brains often occupy perfectly standard female bodies and vice versa - and the entire landscape changes. Suddenly there's the tantalising thought that gender may actually be a spectrum. Norrie's opponent was the NSW Registrar of Births, Deaths and Marriages. We have constructed these as life's three pinch-points, moments demanding propriety. The rest of the time you can wander off into as much weirdness as you like but for birth, death and marriage you must be unambiguously named, typed and tagged. Until now. If there are three gender choices, why not more? Why not an array?

We see gender as fundamental. Gender is the first thing we know about ourselves and the first thing we perceive about others (unless, as racists, we prioritise skin colour). This is why talk of changing and even querying gender can make you feel queasy. If that can shift, you feel, anything can. It's also why so many of the most interesting cultural movements - from Alexandria to Weimar and from '70s punk to '90s ''dark cabaret'' - have been intent on blurring gender boundaries. I speak as a boundary person. I like definition. Much of my life is devoted to it, aesthetically, verbally and urbanistically. To me, defining the colours lets them shine more brightly. Yet perhaps gender is an exception. Or perhaps the mistake is to generalise, applying one rule for all. The history of feminism is, broadly speaking, a continuing progress towards maleness, of one kind or another - from trouser-wearing to public swearing (personal favourite) to promiscuity. A separate process, be it due to oestrogens in the water or expectations in the air, seems to be trending maleness girl-wards, as evidenced by man-boobs, top-knots and house-husbandry. This may eventually produce a genderless melee, where all colours merge into brown, but it strikes me as unlikely. More probable is an acceptance of a gender spectrum, an extension of ''rainbow politics'' to include us all.

Think of it as a sci-fi proposition. What would it mean if sex persisted as a verb but disappeared as a noun? It'd mean accommodating the pronouns hir and zie, as we've accommodated Ms - and maybe extending Ms to include everyone. It'd mean toilet blocks and change rooms, instead of being clumped as male and female, might run from ultra-male one end to ultra-fem the other, with in-betweens self-selecting along the way. It'd end gender-appropriate clothing, behaviours and perfumes and make gender-free parenting look suddenly less nutty. Loading It'd end feminism, since war requires dualism. End sexist movements such as One Million Women. And end the battle for same-sex marriage, since all marriage would be same-sex. (This might be a jolly good thing, given new studies showing gay marriage is fairer, happier and more enduring than straight). And of course it would change the midwife's cry. But to what? Maybe instead of ''it's a girl'' or ''it's a boy'' we could practice, ''it's a [new-four-letter-word-meaning-neonate-sentient-biped-with-near-infinite-potential]''. Hmm, I dunno - what about, say, baby? Twitter: @emfarrelly