As a feminist, pacifistic gamer, I can state with certainty that playing video games has not turned me sexist or violent.
Do I believe that games can turn people sexist or violent?
Depends.
On the large part, no, I don't think so at all. A person with a firm grasp on reality probably won't be influenced by what's being portrayed in games. Someone that can't differentiate between reality and fantasy as well as the "typical adult" (read: very small children, or people that actually have a decreased mental capacity for differentiating the two) probably can be influenced slightly by violent or sexist media - note I said "media," not just "games." But I don't think that's a problem with the media itself; I think that is, unfortunately, something that is involved with the person in question, and should be solved as a "person's issue" (read: psychological aid for adults, and the obvious "growing up" for the young children before they consume said violent media) rather than blamed on the medium in question.
Do I believe that games can turn people sexist or violent?
Depends.
On the large part, no, I don't think so at all. A person with a firm grasp on reality probably won't be influenced by what's being portrayed in games. Someone that can't differentiate between reality and fantasy as well as the "typical adult" (read: very small children, or people that actually have a decreased mental capacity for differentiating the two) probably can be influenced slightly by violent or sexist media - note I said "media," not just "games." But I don't think that's a problem with the media itself; I think that is, unfortunately, something that is involved with the person in question, and should be solved as a "person's issue" (read: psychological aid for adults, and the obvious "growing up" for the young children before they consume said violent media) rather than blamed on the medium in question.