FARGO -- Ashley Johnson, a mother of twin boys who turn 3 next month, thinks kissing her children on the lips is the natural thing to do. "I don't think it's any different from breast-feeding them," ...

When my 3-year-old is in a good mood, she asks for a “true love kiss.” She first heard the phrase during a family viewing of Shrek, but it has since become her signal that she is craving affection.

Our ancient primate relatives—including Neanderthals—may have enjoyed a nice peck on the lips. But researchers still don’t ...