>>Grusta+(OP)
Google's published tech stats suggest the ratio is closer to 7 in 10. Women physicians are 3-4 in 10. Biology appears to be 6 in 10 from what I could find (and is relatively unique in STEM fields, also not out of line with the socialization that animals/horses/veterinarians/marine biologists are often socialized as girls vocations).
And yeah, I think it's a potential contributing factor (one of many). Kids in many parts of the country are socialized that certain things are only for certain genders. It sucks. Let kids like whatever they want.