My teenage daughter and most of her friends are all gamers. They play a lot of the same stuff I like. She's been brought up around games and gaming as a culture. It's just part of her life experience and the story of her friends seems similar.
When she was little, we played Mario Kart and Super Mario Sunshine, as she hit the tween years we played Mortal Kombat (I turned off the blood and fatalities, hold that call to social services) and Street Fighter. Now that she's actually of age to play M rated games, it's just a natural progression for her. Saints Row 4 was the last game she played, though I let her play SR2 a few years ago too. She's played Fable, loved both the 3D Fallouts and Skyrim. She won't play Halo with me because she says her big teenage rebellion is to refuse the science fiction that informs so much of the things I love (it's a gag of course, and a funny one in practice), but she pops off headshots like a pro in her school's gamers club.
So this isn't a surprise to me. It's nice to have released numbers to back it up I guess. As a lifelong gamer in his 40s, it's nice to see that the culture has matured beyond the teenage boy demographic that it used to exist within almost exclusively. Now if only we could do something about the toxic online gaming stuff, we'd really be getting somewhere. *topical wink*