In a word, stress — or at least some form of it. "A more useful insight is that the lines in someone's kiss print indicates the person is probably not good at asking for help from others, or knowing when to let things go," said Bongar. "Some lip reading experts claim there's a distinction to be made if the stress lines are coming from the outside to the inside, or vice versa. I stick with the more general insight, and look for how pronounced the stress lines are: The more pronounced, the more stress, I've found."