I heard this on the radio this morning doing the school run.
The woman they were interviewing was at great pains to point out that it's purely prejudice, that the research shows there's no sex based difference in mathematical ability, and how important it was to see women in academic maths positions, because even now, she finds herself lecturing halls full of men, and in in a faculty of men.
Her elder sister was apparently very good at maths too, and is what gave her the example to aspire to, rather than believe what society told her, and that rings true with me - my mother is very good at maths, and so it never entered into my head that girls shouldn't be good at maths because I had her, teaching me from my very earliest memories. And my experience with my own children, is that with maths, half the battle is having the confidence to give it a go - to launch in and see if you can figure it out.