At first I thought this was a photobooth shot, but the quality looks too good. In fact, it looks like they were posing for the shot in a studio. I'm guessing it is ca. 1940s-1950s, by the haircuts and shirts. They could possibly be brothers or cousins but it's always more fun to wonder whether there was a lot more to a photo than meets the eye. There's a shy look about the man being kissed and a mischievous, possessive one to the kisser which add to the intrigue.