Ok tell me the definition based on gender thats not circular and therefore massively useless
I don't really understand your sentence but here is a good definition:
Sex refers to “the different biological and physiological characteristics of males and females, such as reproductive organs, chromosomes, hormones, etc.” Gender refers to "the socially constructed characteristics of women and men – such as norms, roles and relationships of and between groups of women and men.
The distinction is very important in sociology.
Define nature in terms of male female desires, attraction, why are they attracted to each other?
Natural process... for what?
What is natural when it comes to human sexual reproduction.
Or lets say, what's the natural purpose of sex organs.
Oula.. there is a lot of "strange" things here.
First, I think you have the understanding of Evolution all backward. Evolution is not about "purpose", its natural selection. Sometimes, there is no "purpose".
Secondly, everything is natural as long at it happens naturally. (I don't really know how to rephrase that more clearly)
I don't think that there is rationnal reason why homosexuality hasn't dissapeared yet in every species on earth but the fact is: it's here.
So homosexuality is as natural as people being trans or people being asexuals or people being non binary etc..
Its just something that happens naturally.