Hallucinating Foucault

I'd always thought the narrator was a woman.
Nothing in the 1st-person narrative had given me any doubt. I didn't even bat an eyelid when the narrator found a girlfriend. Actually it rather confirmed my pre-conception that it was a woman because I'd seen this book in the Big Gay Read. The unconventional girlfriend seemed just like those weird lesbian characters which occur quite common in LGBT film/tv (at least lesbian rebels are much more common than gay male rebels)
I was shocked when I read this on p.20:
The prospect of meeting your girlfriend's father, or at least one of her fathers, is very intimidating. I began to panic.
"Should I put on a tie? I haven't got a tie."

Huh? When I finally realised in the next paragraphs that the narrator really is a man, I was wondering whether I should've re-read those 20 pages because I'd had a totally different picture in my mind.