How do you know that your favorite color isn’t influenced, or even entirely decided by biology and chemistry?
Thing is, despite many hypothesis being thrown around, getting support or not most of the time mostly depending on whether or not they fit well with the person’s already established worldview, we know pretty much nothing about the brain, about what exactly is determined by biology and what is determined by culture. Your preferred color could very well be dependent on genetics. In fact I would suspect it probably is to some extent.
And when you say that gender is really influenced by biology, chemistry, etc… : what do you mean by “gender”? It’s not a trick question, it’s really unclear to me. What makes one person, according to you, part of a gender rather than another? You talk about gender being a continuum. But this implies that gender is a monolithic thing, and that all the sub-parts that constitutes this “gender” move together on this, say, slider. But I see no reason to assume that. Each individual characteristic that together constitutes “gender” could have its own independent slider. And some could be very dependent on genetics, and some less, and some not at all. And some of these parts could be biologically related to each other and reflect some sort of biological reality, while we associate others characteristic to them for purely cultural reasons. To give an example, let’s say that what you call “gender” is made of five parts : A, B, C, D and E.
A is 80% determined by biology, B is 50% determined by biology, C is 20% determined by biology. And they’re also related from a biological point of view. If you have a lot of A, you’ll have also a lot of B and a lot of C (for the small part of C that is determined by biology). D is 100% determined by biology, but totally unrelated with A,B and C . We just regroup it with the others characteristics under the name “gender” for entirely cultural reason. And it also has only two positions determined by biology : D+ and D- Finally, E is entirely cultural with no biological basis, and of course as a result unrelated to A, B and C.
So what we have here is a gender where three elements (A, B and C) are moving more or less together, but not entirely so, on three tied sliders with each of these sub-sliders being also influenced, to a different extent, by culture, one element (D) that has only two possible positions determined biologically, and a last one (E) with its own totally independent slider only influenced by culture. And then we look at the whole mess and we say : “this is gender”. And tomorrow maybe we’ll remove “E” from our definition of gender (anyway, it’s just associated with the others arbitrarily) but we’ll add instead a new characteristic F, for equally arbitrary reasons.
That’s more or less how I expect “gender” to work in reality (except much more complicated). I definitely don’t expect a simple continuum determined in a large part by biology as you seem to do.