There's nothing about guitar, bass, or drums that keep average-sized women from playing them. Examples on youtube abound. Look up Meytal Cohen's drum covers, for example. She looks like she's about 115 lbs and plays a mean Danny Cary.
I've always wondered why there aren't more girls in music. Rock is mostly dudes and jazz even more so. It's gotta be some sort of cultural thing I guess. There are lots of woman classical musicians and bluegrass, country, and folk have a fair amount, too. But somewhere along the way rock became some kind of a macho thing. Jazz's lack of woman players goes back a lot farther since jazz is a lot older, but even today go to a local jazz jam and it's mostly dudes. The local jam I was going to had one woman pianist who would sometimes show up, and there was this one woman electric bassist who was astoundingly good, but she only stopped by the one time. Esperanza Spalding is an awesome jazz bassist but she's kind of in a class of her own.