This thread reminds me of a comment my Mum made once

"you should never kiss a baby on the lips"

It came from generations ago when there were lots of diseases that were fatal back then such as Colds, Flu, Polio, Chicken Pox and all the things that there are now immunisations for now.
It came about as you never new you had the virus until you were gravely ill, so kissing a baby on the lips thus passing on your saliva would then give them the whatever you had and usually ended up fatal .

On saying that....I kiss heaps and heaps! Not always on the lips, everwhere I can. I loove kissing my kids and they giggle and squirm when I just can't stop!