I used to get into terrible trouble for pointing out that well into living memory, and even more so when I used to say this 10 or 15 years ago, "homosexual" was only ever an adjective rather than a noun, and only ever referred to acts rather than to persons.
But now, even Matthew Parris, who unlike me is old enough to remember it, says this, and he does so in the pages of The Times. The reaction has been predictable.
Yet although this may not necessarily be true among today's very young, at least until a few years ago most gay men and almost all lesbians had had at least some heterosexual experiences, often well into adult life.
What times we inhabit, that sexual orientation is held to be fixed, while "gender", which has always been known to the rest of us as biological sex, is held to be "fluid". And woe betide anyone who dares to challenge either of those propositions.