Harry is arguing from the extreme, suggesting that very rare genetic disorders are normal: they are clearly not normal, but defective, often having other health defects in addition to their sexual development. We respond with kindness to these people by assigning them a gender based on their external genitalia at birth, rather than their DNA. People with Swyer syndrome are typically raised as girls and have a female gender identity, and are given female hormones to induce a normal puberty, but are sterile.
Scientifically sex is determined by DNA (XX or XY) but phenotypic sex, and therefore gender is determined by the presence or absence of a penis. Earlier comments such as “Look between your legs” are therefore good advice.
That rule is clear from the language used to describe them: “Human males with a XX karyotype are sterile males with normal female chromosomes (1 in 20,000 male births)” and “patients with Turner’s syndrome, with XY chromosomes who grew up as phenotypic females” proves that.
“ Females typically have two of the same kind of sex chromosome (XX), and Males typically have two distinct sex chromosomes (XY). Exceptions to these generalisations happen in the cases of XX males or XY females, or other syndromes.” https://en.wikipedia.org/wiki/XY_sex-determination_system
Harry is correct that the development of the genitalia is controlled by the SRY gene which has to be on the Y chromosome for normal male development to occur.
“A single gene (SRY) present on the Y chromosome acts as a signal to set the developmental pathway towards maleness.This and other factors result in the sex differences in humans. Humans, as well as some other organisms, can have a chromosomal arrangement that is contrary to their phenotypic sex; for example, XX males or XY females.
That is what he meant by “ 50 years of scientific advance in sexual biology” but he draws incorrect conclusions from the discovery of rare genetic defects, extending their moral cover to people who choose to simulate rare genetic defects they were not born with. XX Males and XY females are a tiny minority and are correctly handled by recognising their apparent, rather than their underlying genetic gender.
To extend this logic to physically normal males and females who have a mental condition resulting in their wanting to change gender is quite wrong, and results in incorrect treatment of these patients. Rather than being cured of their mental disorder, or at least treated for it, this fool’s logic leads to normal, fertile males being castrated and mutilated to vaguely resemble a female, or to women having their breasts removed and being sterilized by testosterone treatments to induce male body hair. I know of no surgery to give such a woman a functioning penis, so “gender reassignment surgery” is a cruel lie.
After surgery the outlook for a normal life is bleak: their original gender has been removed, and replaced with one than does not work. Transgender Women cannot give birth; and Transgender Men cannot father children, but their mutilation means they can never be cured of their original mental disorder because it has now been apparently validated by the surgery.
The fact that so many “Trans” people commit suicide after the operation is a clear indicator that gender reassignment surgery is a horrible mistake, and encouraging more gender-confused people to go Transsexual is therefore morally wrong. Treat them with psychology, not with surgery!
I will relate socially to people according to the gender they present as, but this is out of consideration for their feelings, out of kindness and good manners if you like, but this does not imply that I approve of their decisions.
Born XY Women and XX Men are a different case: they were handed a bad set of cards by their genes, and are just making the best of a bad situation. They deserve our respect as well as our sympathy.