I have to agree with Forks there. The way you were raised determines your pda alot.
Also, shy people will usually shun away from that. But even very outgoing people can be that way, it just depends a bit on the person him/herself.
It's mostly for selfconscious people that pda does tend to single you out more than any other action. Hell, you can be standing on a stage, dancing and going all out and have a blast, just because there are other people doing that too. But in case of pda, it's something they perceive as: getting singled out and getting intimate, which for them is reserved mostly for private moments & locations.
And yes, I'm a self-conscious weirdo myself. So maybe I'm just talking about myself
