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Stephen O’Rahilly vs. transgender people

Stephen O’Rahilly is an Irish-British physician, scientist, and anti-transgender activist. O’Rahilly researches the molecular basis of obesity, insulin resistance, and metabolic disease.

O’Rahilly is an advisor to anti-trans group Sex Matters.

Background

Stephen Patrick “Steve” O’Rahilly was born on April 1, 1958 in Dublin, Ireland. O’Rahilly attended Beneavin De La Salle College in Finglas before studying medicine at University College Dublin, graduating in 1981. O’Rahilly completed a medical degree in 1987.

O’Rahilly conducted research on type 2 diabetes and insulin resistance at the University of Oxford and Harvard Medical School. O’Rahilly subsequently joined the University of Cambridge. O’Rahilly served as Director of the Medical Research Council (MRC) Metabolic Diseases Unit, co-director of the Institute of Metabolic Science, and scientific director of the National Institute for Health and Care Research (NIHR) Cambridge Biomedical Research Centre. O’Rahilly has been an associate faculty member of the Wellcome Trust Sanger Institute and an honorary consultant physician at Addenbrooke’s Hospital, Cambridge, as well as a professorial fellow of Pembroke College, Cambridge.

O’Rahilly was elected a Fellow of the Academy of Medical Sciences in 1999 and a Fellow of the Royal Society in 2003.

O’Rahilly was married to Suzy Oakes from 1990 until Oakes’ death in 2011. O’Rahilly later married journalist Philippa Lamb.

Anti-trans activism

On the Sex Matters profile, O’Rahilly stated:

“I am concerned about the conflation of sex and gender in public discourse for a number of reasons.

  1. As a medical doctor and endocrinologist I have long been concerned that the evidence base for the use of hormonal and surgical treatments for gender dysphoria is very weak and that the use of such powerful, permanently life-altering therapies should be much more rigorously evaluated and tightly regulated. 

    I am also very aware of how the three periods of high androgen exposure (inta-uterine, post-natal and pubertal) to which biological males are exposed have profound and irreversible effects on development and anatomy. In contrast to the gametic, chromosomal, hormonal and anatomical aspects of sex, each of which can be meaningfully assessed, I do not believe that it is possible to define gender identity as a stable and measurable trait.
  2. As a scientist I am very aware of the centrality of sex to the understanding of the evolution and fundamental functioning of our own and many other species. Losing the meaning of sex is detrimental to rational scientific discourse. 
  3. As a human being I have been horrified to see many societies prioritise the feelings of a small number of men wishing to present as women over the safety and dignity of women, particularly those in vulnerable situations such as prisons, hospital wards, rape-crisis centres and domestic-abuse shelters. I am also very concerned about the widespread persecution of those who make factual statements about sex versus gender.
  4. As a sports enthusiast, I am very concerned about the unfairness of allowing male-bodied people to compete with females in sports where the physical advantages of having developed under the influence of high testosterone are abundantly clear.”

In a July 2025 article in The Telegraph on academic freedom, O’Rahilly stated:

“For me it was the need to be able to discuss the issue of biological sex and its importance for how we structure medicine, law and society that made me feel I could no longer be simply an observer. I am pleased to say that I received no pushback from the university about any public statements I made.”

Anti-trans coverage

Mosey, Roger (July 26, 2025). My chilling decade on the front line of university culture wars. The Telegraph https://www.telegraph.co.uk/news/2025/07/26/cambridge-universities-britain-free-speech/

Resources

Sex Matters (sex-matters.org)

Wikipedia (en.wikipedia.org)

X/Twitter (x.com)

Bluesky (bsky.app)

University of Cambridge Institute of Metabolic Science (mrl.ims.cam.ac.uk)