There is a new-ish magazine available called She Shreds. It is important. Here's why:

I remember being a teenager and trying to explain to other teenagers why more girls don't play guitar. It was relevant at the time because I was leading and playing in worship bands in churches and almost every permutation of every band was the same: boys on drums and guitars, girls on vocals (and keys were the gender wildcard). I was annoyed.

My reductive theory was this:

We subconsciously do things based on what we think will make us more attractive.
Girls are attracted to talent.
Boys are attracted to looks.
Obviously, developing a talent (playing the guitar, for instance) takes time and energy.
Spoiler: being pretty takes time and energy, too.
There are only so many hours in a day.

There were, of course, a lot of other reasons (precedent, culture, etc) but this was my best shot at trying to work it out.

Ten years later, change is afoot.