Agreed. And most of the on-field stuff in those sports (phantom tags, acting like you caught a ball you know you trapped, flopping for foul calls, trying to rip open a cut on your face to get those extra 2 penalty minutes, etc, etc) would fall under that category. However, there are still a lot of bad apples that go the next step (corking bats, steroids**, trying to injure QBs, undercutting jump shooters [I'm talking to you Bruce Bowen], etc) that I wouldn't put in the category of "peer pressure."
I'm simply saying that there is no reason to think that there aren't a few guys like that out there that also happen to be great golfers.
**I'd concede that you could make an argument for steroids in baseball to fall under the "peer pressure" category from 1998 through 2004 or whatever it was.