I think guys are more likely to troll because society doesn't let men vent as much as girls. Men are not suppose to have hurt feelings so instead we hide our feelings deep inside and unleash them on the internet.
From what I've seen? Girls, but that's only cause there are more girls on this site than guys. Per capita? Probably about even. But how they troll is different. Most girls I see trolling aren't attacking anyone, just joking around. Most guys I see trolling are being douches.