What the Causes of "Homosexuality" Taught me about Transgender

The following is a summary of my longer piece you’ll find here and which includes links to my various data sources.

From Sexuality to Gender

In exploring what causes people to be gay for my website I was drawn into the more complex topic of transgender identities. Science has now shown our sexuality is overwhelmingly shaped by biological factors—neurological, genetic, hormonal, and chromosomal—mostly before birth. Social environment seems to play very little to no role, especially for male same-sex attraction. (See https://www.affirmingevangelical.uk/made-gay)

Public attitudes have shifted accordingly. In 1983, only 17% of Britons saw nothing wrong with same-sex relationships; by 2023, that figure had risen to 67%.

Yet, while acceptance of LGB individuals has grown, attitudes towards transgender people have hardened. Between 2019 and 2023, the percentage of people admitting prejudice against trans individuals doubled from 18% to 36%.

This tension came to a head on 16 April 2025, when the UK Supreme Court ruled that “sex” under the Equality Act simply meant "biological sex" assigned at birth. Many trans people felt devastated, while many "feminists" celebrated this as a return to “common sense.” Supporters cited Genesis 1:27—“male and female He created them”—as divine confirmation of binary sex.

Ancient Wisdom and Gender Diversity

This binary view of sex would have surprised many ancient thinkers. Hippocrates and Galen saw sex as a spectrum, with many shades between male and female. The ancient Hebrews, too, recognized complexity in our gender. The Talmud lists seven gender categories, including androgynous and aylonit (assigned female at birth but lacking secondary female traits).

So, what causes transgender identity? There's been far fewer studies of this compared to causes of homosexuality. But there is clear evidence of biological roots for many. There are also theories suggesting social factors may play a role, e.g. in “rapid onset gender dysphoria” amongst adolescent girls, but this remains yet unproven.

Intersex: The Overlooked Reality

Biological variations don’t just affect sexuality—they also shape sex itself. Intersex individuals are born with mixed sexual characteristics. It’s occasional but not rare: up to 1.7% of us may be intersex in some way – equivalent to the population of Russia! A rather smaller 0.5% are estimated to have mixed sexual or reproductive organs – equivalent to the population of Poland. The large majority of that 0.5% only have internal mixed organs, e.g. women with internal testes or men with ovaries and uteruses. A much smaller number – about 0.05% of the world have externally visible mixed organs – equivalent to the population of Croatia. So, about 97% of intersex people only have internal intersex traits, mostly involving chromosomal or hormonal variations.

These complexities challenge the simplistic notion that sex is always binary. As microbiologist Dr. Rebecca Helm explains, sex involves a complex web of genetic, chromosomal, hormonal, and cellular factors. For example, the SRY gene—critical for male development—can sometimes jump from the Y to the X chromosome, creating chromosomal males with female bodies.

Why Intersex Matters for the Trans Debate

Transgender individuals are those who identify with a different gender to the sex they were assigned at birth. Intersex individuals are those whose biological sex is in some way mixed. They’re different things but they do overlap. Many trans people may unknowingly be intersex, if their traits are internal - like 97% of intersex people - or if they were surgically “corrected” at birth. Only 0.54% of the UK population identified as transgender on the last census. That’s about a third of the estimated 1.65% who are internally intersex.

I’m unaware of any direct research on this point. However, it would seem likely that many of the small minority who identify as transgender do so because they’re one of the larger minority who are biologically intersex. But they won’t know this unless they’ve had the right tests – just like Caroline Cossey. She was a former Bond girl, who appeared externally male and so was assigned male at birth but she'd always felt female. Only just before her gender reassignment surgery did tests reveal she was intersex, with a very unusual XXXY chromosome pattern—more female chromosomes than most women! She remained transgender, but the cause for this was now identified – she was intersex.

This biological reality complicates the anti-trans argument. If a trans woman like Caroline Cossey is chromosomally predominantly female, how can society deny her female identity, especially after she'd had full reassignment surgery? Reading her story in the 1990s convinced me of the trans case, even as I remained very homophobic. Ironically, many are now pro LGB but anti TI!

Biological Crossovers Between LGB and TI

There’s also overlap between intersex and LGB identities. A recent EU study found that a huge 69% of intersex people identify as LGB, compared to just 3% of the general population (according to the last UK census). About 1.7% of the general population are estimated to be intersex - about half the number identifying as LGB. This suggests that biological variations influencing sex may also shape sexual orientation. I’m aware of no studies confirming any figures, but the maths suggests that a significant minority of LGB individuals because they are also (unknowingly) intersex. Even for the non-intersex majority of LGB individuals, science now shows what usually causes their sexuality is that they have a little more of the opposite sex thrown into their biological mix/history. (Again, see my website link here )

Conversion therapy offers further insight. Numerous studies have now shown it’s completely ineffective for changing sexual orientation and very harmful—consistent with the idea that sexuality is biologically rooted. Some of the same studies also looked at attempts to “cure” gender dysphoria. These had been similarly unsuccessful, again pointing towards biological causes. (See my website, part four of The Answers here )

Humility and Mystery

There is much we don’t yet know about why some people identify as trans. We know some trans identities stem from intersex traits. Others may come from biological factors we can’t yet measure. Social causes may exist for a few. However, currently overwhelmingly the main pointer seems to be biology. Over the past 30+ years science has taught us so much about the biological causes for homosexuality, making many previous judgments about the causes look rather foolish. Who's to say what science may teach us over the next 30 years about the causes of transgender identities? 

Rethinking Scripture

Genesis 1:27 says God created humans “male and female” But this doesn’t exclude intersex people. The phrase uses merism—a literary device used elsewhere in Scripture, expressing totality through extremes, like “dark and light” or “young and old.” It’s not a denial of twilight or middle age, but a poetic way of saying “everyone.”

The Talmud’s recognition of gender diversity supports this reading. God’s image includes the full spectrum of human identity—male, female, and everything in between. Jesus himself refers to “eunuchs born thus from their mother’s womb” (Matthew 19), seemingly acknowledging natural sexual variation.

And aren't most of us biologically mixed up in different ways,? I'm a very heterosexual, cis male but can certainly see other variations to the "normal" in myself! And don't these myriad differences mostly come about from the complex biological processes through which God “knit us together in [our] mother’s womb” that make each of us “fearfully and wonderfully” and uniquely different? 

God’s creation is full of diversity: not just night and day, but dawn and dusk; not just primary colours but the full spectrum of the rainbow! This richness should be celebrated, not feared.

The Harm of Denial

Gender identity is central to human dignity. Denying someone’s declared gender—especially after legal recognition—causes deep psychological harm. The Supreme Court’s ruling effectively invalidated gender recognition certificates. It made no distinction for the biologically intersex or those surgically re-assigned. So, even an intersex trans women with full female external parts like Caroline Cossey is legally forced into male spaces. Meanwhile, testosterone-fuelled trans men with beards and pump action penises must use female facilities. This does little to improve female safety and much to increase suffering. Research finds no evidence that transgender inclusive bathroom policies have resulted in increased assaults to women (other than trans women occasionally being assaulted by other women). (See e.g. the UCLA study referenced here: https://www.nbcnews.com/feature/nbc-out/no-link-between-trans-inclusive-policies-bathroom-safety-study-finds-n911106 )

There’s no one-size-fits-all answer to every trans issue. Sports participation may require different considerations to bathroom access. But blanket denial of trans rights is simply unjust.

The Myth of the anti-trans fundamentalists

There are some complex issues in the transgender debate. But we need to be very wary of the anti-trans fundamentalists who enter this debate on a false premise: that sex is always binary and obvious. (And yes, I know, there are fundamentalists on the other side too!) Science clearly shows otherwise. Although much remains unknown, chromosomes, hormones, and cellular responses all contribute to a diversity in our sex and gender.

A clue to that false premise is that one of the greatest anti trans fundamentalists is Donald Trump, who continually denies proven facts—from climate change to autism to gender biology. His rhetoric fuels fear and division, distracting us from the real threats like economic inequality and environmental collapse that inconveniently block his greedy agenda.

Unlike him, many anti-trans advocates are sincere and well-meaning. But, I believe, some of them - the anti-trans fundamentalists - have been misled by powerful forces that exploit fear for political gain. Scripture warns us that the ultimate force behind all deception (the deceiver of the deceivers) is supernatural.

Jesus warns us that the devil "is ... the father of lies." (John 8:44). And Peter warns us that he “prowls like a roaring lion, looking for someone to devour” (1 Peter 5:8) through his lies that lead to humans’ destruction, just as he’s done right from the beginning in the Garden of Eden (Genesis 2). I've certainly been deceived by him before over many things, as had Peter! We all need to be wary of his deceptions.

A Call to Love and Acceptance

Jesus naturally most aligns with the marginalized—refugees, racial minorities, and, yes, gender outsiders. To reject trans people is to reject those whom Christ embraces. We must love our neighbours as ourselves (Romans 13:10), treating others as we would want to be treated in their shoes, doing them good not harm.

Some trans people may look a bit different to us cis people, just like gay couples look a bit different heterosexual couples. But we should accept people as God made them—“born thus from their mother’s womb”—and celebrate the diversity of His creation!