Alright ladies, need some insight...

I have an amazing 7 year old step son who is such a lover!!!! On his mother's side of the family everyone kisses each other on the lips. Grandma, grandpa, mom, dad, aunts, uncles, brothers, etc.

My husband and I didn't grow up doing that so when he is with us we commonly kiss him on the cheek.

Well I just had a baby a few weeks ago and my step son is over the moon excited!!! But he keeps kissing her on the lips. And I really dont like it. He already kisses all of his family members on his mothers side on the lips (even his little brothers) and I am concerned about the germs and viruses that can be spread.

How do I politely tell him not to kiss his sissy on the lips without breaking his heart? It makes me so nervous that it will hurt his feelings.... but I also cringe each time he kisses her.