As a scientist I am only convinced by observables. I am rarely in a position to examine the genetalia or chromosomes of other people.Thus the only viable data is from the invidvidual concerned, so I see no alternative to accept whatever "identity" they want.
As an Englishman I of course look to Shakespeare who tells us "All the world's a stage, And all the men and women merely players". Some people act like women, others do not, one of my drinking buddies acts as a dog on childrens TV another is teaching young women how to act like 1920s lesbians, some people "act black" including occasionally my teenage very white boys. I observe this all and fail to care very much, because the one uniquely English virtue is not giving a fuck about things that don't affect you.
Which leads to my posiiton as a pimp, where I don't care whether someone pisses sitting, standing (or as ithe case with some people), into a bag as long as I can sell them.
As for "skirts", the royal Connor tartan is of course grey and given that I am the minority of wilmotters who has had formal training and qualification with both the cutlass and Lee Enfield .303 rifle, I would happily duel with anyone who challgenges me on this.