Kissing is a great example of a balance between the nature and nurture we always talk about. We see similar behaviors across the animal kingdom. So there is something innate. It’s also something we pick up, not just from family and friends but it’s also exported by Hollywood. It is part of the community you’re in and what you’ve been exposed to. Decades ago, anthropologists estimated that 90% of cultures across the world kiss. That was before the rise of the Internet and the frequency with which so many people travel around the world, so I suspect that percentage is even higher today.