Gender is not a biological function. Gender is a social, psychological, and cultural construct that is developed through socialization. Gender identity is a person's internal sense of self, whether they see themselves as male, female, or another gender. What 'scientific reality' do you think is threatened. Female and male exist. A spectrum also exists according to DSD. Are you stating that the genetic spectrum found in those with DSD should not be labelled as anything other than male or female...i mean...you're asking for science, so
here is science. Make sure to read all the linked refrences and not just rely on wiki.