Here is Winston's contribution to the GRA debate in 2004.
"Lord Winston: My Lords, I reluctantly join the debate at this stage of the Bill. I apologise for not being in the House at Second Reading and for hearing only part of the Committee stage. However, I feel so strongly about the amendment, as well as about Amendment No. 128, that it is important to put on record the medical facts.
As a practising obstetrician and gynaecologist who as been involved with reproductive medicine and the definition of sex in both animals and humans for the past 30 years in my research, I can only reiterate the comments of my noble friend Lord Turnberg.
The definition of sex is extremely complicated. It is not just a question of chromosomes. It is possible of course to have chromosomal sex and it is probable, though by no means certain, that all of us in this Chamber have chromosomes that are either XX or XY. However, even in the case of Turner's Syndrome, which my noble friend has just described, it is possible to have an XY mosaic, with some of the cells carrying a Y chromosome and some having a deleted X chromosome. The variations of that syndrome mean that people may have different degrees of masculinity or femininity.
Most practising doctors in the field would describe sex on six, totally separate, definitions. Those definitions can be chromosomal but, more importantly, they are genetic. It emerges that genes on the Y chromosome are not the only genes that define sex. Although the SRY gene is by far the most common and important, there are genes on chromosome 17, chromosome 11, chromosome 10, chromosome 6 and chromosome 3 that can, in exceptional circumstances, determine sex of various kinds. Those people can carry on a completely normal life.
Genetic sex is therefore no less important than chromosomal sex, but that is not the end of the story. There is also hormonal sex. Some people will produce hormones that will tend to feminise them, while others will be masculinised. That can happen in utero. Good evidence has emerged from Professor Waters of Monash University in Australia - he is now long retired - that suggests that some people who become transsexuals later in life have been exposed to an abnormal surge of either male or female hormones during pregnancy. That has caused them to have a different psychological sex from their genital sex. Psychological sex of course depends on brain function. That also varies greatly and is probably genetically determined, but so much exploration of that subject is being conducted that is not fully understood.
Genetics is rapidly changing our understanding of where sex is determined. But to define it simply as genital, hormonal or, as the noble Lord, Lord Tebbit, seeks to do, as gonadal, is a travesty of what really happens.
Let me give one example. Janice was the most beautiful woman, who came to my unit some time ago. She was six feet tall, and had been brought up as a woman. She had very well developed breasts, a perfect physique, and was actually XY. She did not find that out until she was 20. Some people with XY dysgenesis believe themselves to be female and relish being female. Others find that when they are actually male because of their chromosomes, they entirely change their view psychologically.
I should like to make the point made by Robert Jaffe, now retired, a very distinguished endocrinologist. He says in his chapter on reproductive medicine headed "Disorders of Sexual Development":
"It is crucial that the clinician who deals with patients with genital ambiguities be sensitive to the emotional as well as the physical needs of the patient. The patients frequently have a great deal of confusion and anxiety about their sexual roles. Whereas genetic, gonadal, hormonal, and genital sex may be of prime importance to the physician, the gender identity (that is, how the patient views himself or herself) and the sex of rearing are paramount in determining the patient's sexual identity".
Robert Jaffe is effectively saying that there needs to be an understanding of the autonomy of the person concerned because, on the whole, they are the best people to judge how they feel about their sexuality. That is true of the 200 different mutations which could have affected Janice, my patient. There are so many different fluctuations in this broad spectrum of sexuality that I urge the House to be very cautious about defining it in terms of chromosomal, genital or any other simple definition. It simply is not medically just, and I am sure that it would produce bad law.
He knows there are only two sexes in most species on the planet, and that in humans sex is binary and immutable.
He knows there is no ambiguity in ostensibly all human beings bar a miniscule cohort of certain, specific DSDs.
Neither Klinefelters, not Turner's syndromes are amongst the category where sex is ambiguous.
He knows this bill did not propose to address any people with those specific DSD conditions.
He knows there are only two gametes, eggs and sperm, and that each of us develops along one of two pathways to produce one or the other.
Had he logic (or integrity), he should have concluded that if, as he argues, male and female are not references to ones reproductive class evidenced by chromosomes, genetics, gonads, genitalia, hormones or whatever his 6th criterion apparently is (psychological sex?), then there is nothing left to BE referenced as a determinant of male and female, other than changeable societal stereotypes of a particular culture and era.
There are two human sexes. They cannot change. They refer to our reproductive class, in our species as in almost all species on the planet. The definition for male and female applies to our species in the same way as it does other species.
There is no logical, medical or possible way to identify as a member of the sex class that makes large gametes if you are not an example of that class.
Sex is not an identity.
A person with penis, testicles, prostate, a Y chromosome and an SRY gene is not female, never will be, and does not in any way embody anything female.