I have been wondering that for years Taz, though I have always suffered from unwanted hair, it can be genetic especially if you have a Mediterranean or Asian blood, and as I have an Italian inheritance I have always blamed that. Chinese women don't seem to have this problem.
My sister and one of her teenage daughters suffers too ( she was diagnosed with PCOs) and it is very upsetting.
Personally after doing research I think that that for some women and more so after menopause, that the hair cells become sensitised to the testosterone that we produce even in tiny amounts for the rest of our lives, the tiny amount of estrogen that the ovaries continue to produce is not enough to counter the testosterone.
It could also be that progesterone had a part too, we stop producing that at menopause and some women never produce enough, even during the years from the start of menstruation to menopause.