In an interview last month with the BBC, Hillary Cass said:

“There are a tiny number of people who will never be comfortable with their biological sex, with the gender associated with their biological sex.”

…

When asked how many children with distress about their gender would experience that same distress into adulthood, Cass said it was impossible to assess precisely, but it would be a “really tiny number”.

The paediatrician added: “When the clinic started, there were about 50 children a year in the UK, and then by the time I started my review it had shot up to 3,500 a year.

This surprised me. A common figure for the proportion of trans people in the UK is 0.5%. This was confirmed by the 2021 census, where ~0.5% of adults recorded themselves as not being cis. ~0.1% identified themselves as trans men and ~0.1% as trans women.

There are about 750 000 children in each year cohort. So if every trans person realised they were trans as a child, we would expect about 3 750 trans children to discover that they were trans each year.

If only a “really tiny number” of trans children were actually trans, this would imply that the vast majority of “true” trans people would only discover their transness as adults. This is ludicrous for several reasons. Firstly, this ignores history: a major reason why many trans adults (including me) discovered their transness as adults was because they grew up in a cis-supremicist environment with limited or no knowledge about non-cis possibilities. Current children have much better access to information about trans matters. Secondly, it’s just implausible. What biological or social reason could possibly mean that most cis people were right about their gender identity as children but most trans people were wrong? And finally, if this was right, we’d expect to see large numbers of detransitioners in other countries that are more trans-affirming - we don’t!

The only other plausible explanation is that Hillary Cass believes that most current trans adults are not actually trans. That with appropriate medical help, most trans adults would discover that they were actually cis. It’s quite plausible someone could think this - it’s part of “gender critical” ideology, held by the party that was in government when Cass was commissioned to write her report.

So, unfortunately, Cass’ recent remarks to the BBC suggest to me that she’s aligned herself with transphobic “gender critical” ideologues.