I think your angle is a bit reductive.

Conversations or interactions generally don’t go from 0 to how-dare-you-not-care-about-my-baby instantaneously.

For example, in a cafe, order coffee, I’ve never met the barista before, they’re not going to flop out baby photos and grill me about how much I don’t care about their kidlet. They might make casual conversation, how are you, great day, bit tired, newborn up all night, oh I have a newborn too, she’s been unwell, yeah ours had HFMD last week, oh that’s tough, is she better now, was the fever bad, and so on and so forth. What I’m saying is, it’s through the too and fro that you guage how interested someone is in the things that are important to you.

If my sister had a child then she would probably just expect me to care about her new baby because she’s family and we see each other every week and the new baby is going to be part of my life for the rest of my life.

Another thing that happens is… people just get excited about things and that’s ok too. I became a new father almost a year ago. To me, it’s the most amazing thing that’s ever happened to me. Of course I understand that it’s not very amazing to anyone else, but for those first few weeks of course I was excited about it. It would be fine if I were to “overshare” with my barista, but it would also be fine if they were to tell me to keep my baby photos to myself.