As a kid I wasn't aware of the usefulness of these subjects, all I knew was that they didn't come naturally, and I found them anxiety-inducing, so I avoided them and no one pushed me to persevere. Plus I didn't go to a particularly good secondary school, so that didn't help at all - I took the fact that I didn't do amazingly at GCSE in these subjects to mean that I was bad at these subjects, not realising that actually it was just a case of not working enough at them and not having the best encouragement or teaching in them.
These subjects were dominated by boys by the time it got to A Level, and this sent out the message that they weren't the place for girls, and as an insecure young girl you're unlikely to push against that unless you already know that you have significant natural ability in these subjects, which I already lacked confidence in hugely thanks to my experience in secondary school.
I really do wish someone had pushed me and made me realise that these were options for me when I was younger, as once you've made A Level and uni degree choices, it's already too late.