I was referring to the "Revenge of the Nerds" trope, which involves nerds who are men. But as to your point, the "nerd" characterization arises not only from the field of interest, but the hyperfocus nature of the pursuit. Hyperfocus behaviors get coded as "nerdy" in men but don't get coded as such in women. For example, my daughter, my wife, and I have the same personality. My hyperfocus interests as a teenager, such as computers, got coded as "nerdy." My daughter, meanwhile, hyperfocuses in the same way on knitting or drawing, but those don't get coded as "nerdy" at all.

I think hyper focus on anything is more likely to be classified as "nerdy" today. People will say "I'm a huge guitar nerd" or "I'm a huge gardening nerd" or whatever.

Nerd-dom in women is also only judged if we don't adhere to the social requirements of womanhood. You can be as obsessive as you want as long as you're bubbly, socially adept, and take care to look pretty. Our interests aren't considered a necessary component to our identity culturally in the same way men's are.