In the past many girls were brought up to expect to be supported in life by their husbands, and I suspect, saw no point in concentrating on 'difficult' subjects rather than ones they really enjoyed. Boys knew that they were going to have to earn their keep all their lives and probably support a family, so were more likely to knuckle down to difficult subjects, and get interested in them, because they would be the key to a secure and reasonably well paid career.
That's pretty similar to what Birbalsingh said, and it’s not correct, in my view.
Physics and maths aren’t hard. They just need people to pay attention. If the suggestion is that English, or French, or History are “easy”, then I don’t believe that’s the case. People don’t get interested in something after they knuckle down to it, they are interested in something and get on with it. But someone telling them its hard and they’ll have to knuckle down, makes it seem unattainable, so they go for something perceived to be “easier”.
varian’s mention of C P Snow is relevant. My friend across the corridor in Halls of Residence was studying English. She was always amazed that I had novels on my bookshelf along with the physics and maths books. And scientists are creative; you have to be creative to code, for instance. I think it’s a misconception that science is about learning the rules and churning them out over and over. And all scientists should strive to be disinterested Nannee49 