Cousins can have a whole conversation with one word from a family trip ten years ago.

Shared history compresses. A single word stands in for a whole week, who said what, who got sunburnt, and the reason it was funny, and nobody outside needs to be told because nobody outside can be. That shorthand is the actual evidence of a long relationship, more than anything either of you could say about being close.

The stock of it only grows if you keep making new memories with the same people, which gets harder as everyone’s schedules split. Say yes to one family thing you were going to skip this year. And when someone marries into the group, explain the references rather than leaving them out.