In a very small survey (okay, it was just one question) I did on Facebook, I wondered why nearly 100% of the population in Japan holds up one - or sometimes both - hand(s) in the "peace" sign when having their photo taken.
One FB Friend said it was started by the camera makers many years ago. So, I did a wee bit of Internet research and found out that yes, Konica perpetrated it, but it also may be a holdover from the American hippies of the 60s / 70s era.
The practice seems to have spread to other Asian countries too it seems.
In the west, we say cheese, but in Japan you are as likely to hear someone say "peace" when being photographed and the photographer will often say "cheeeezu!"
You can see why people say cheese in a Wikipedia artile - basically, it's because taking a bit of cheese is supposed to resemble a smile.
But, ask most any Japanese why they make the peace sign and all you're likely to get is a puzzled look - because they don't know either.