Apparently.
If a school were to hypothetically respond with this ridiculous statement when a request is sent to them to reintroduce single-sex PE lessons, are there any websites or documents that posters on this board would recommend to dispute it? Ideally from sporting bodies or other official sources.
It doesn't matter either way whether the information is about gender identity or not. The question relates to single sex sport, regardless of whether students have a gender identity that differs from their sex or not.