"genitals dictate the gender"
Genitals determine sex.
Gender is socially constructed.
We cannot choose our sex.
Gender is a spectrum. Some aspects of gender may or may not be shaped by our biology. Mostly gender is socially constructed.
There are females who, due to their personality, physique, mannerism, voice etc., appear more 'feminine' or 'masculine' than other females within a specific cultural setting.
There are males who, due to their personality, physique, mannerism, voice etc., appear more 'feminine' or 'masculine' than other males within a specific cultural setting.
And then there are females who long to appear 'masculine' and males who long to be 'feminine'
And then of course there are females who long to appear more 'feminine' than they feel they are and males who long to appear more 'masculine' than they feel they are.
Sex IS, it cannot be chosen (unless through extreme medical intervention).
I say, let people be who they feel they are. Men and women ought to feel free and comfortable to dress and behave in a way that suits their gender identity.
Gender is about appearance. Sex is biology.
When it is sex that presents key binary difference people ought to be categorised by their sex not self perceived gender.
E.g.
Sports competition segregate by sex if being male presents an advantage in the discipline (probably not ballroom dancing):
Health and medical sector segregate by sex:
Fashion, marketing, music, arts etc. don't segregate at all.