I (f32) and my family have always been close, but I never realised how strange our family traditions must be to others until my son (m18) was surprised by his girlfriend(f18).

On Sunday, she knocked on our door and I let her in and told her that my son was in his room. She thanked me and went upstairs. About 1 minute later, I heard her screaming at him to explain something. I realised that my son must have been cuddling his sister (f20) and was asleep with her, as they share the same room. I know it is a bit strange for siblings of that age to sleep together in the same room, but in this economy we cannot afford a less modest home, and the other room is mine and his father’s (m47). She thought this was disgusting but I think that she doesn’t understand how families work as she is an only child.

Later on, they went downstairs for dinner, and as my son set the table I thought I should show his gf some more of our family dynamics, so I grabbed him by the shoulders and we kissed. It was straight on the lips as we usually do. This was evidently too much for the girlfriend as she screams wtf. I got upset by her outburst (it wasn’t even that extreme- we sometimes lick each other’s lips too) and asked her to explain herself. Apparently, our family is ‘way too close’, only because I kissed my son on the lips after he was ‘spooned’ by his sister while sleeping. This was so upsetting for me, I just wanted to show her how our family works, so I asked her to apologise. She just ran out of the house.

My son told me later that she won’t answer his texts or calls now, so I told him to tell her that we only kiss like that as a greeting, and that we sometimes surprise lick each other’s lips to tease each other. Idk why having a close family is an issue. My son is now feeling depressed because she isn’t used to such normal behaviour and now won’t talk to him, but I’m sure she’ll come around. As I reflect on Sunday, however, I found myself wondering if I went too hard on her after kissing my son. It was just normal but she is an only child after all, so she may not have a real sense of normalcy. AITA?

Edit- I think people are misunderstanding me. We don’t lick each other on the lips all the times. We only do it sometimes to tease each other. Kinda like tickling but on the lips.