Prior to having kids, people usually thought my wife (Chinese ethnic, Thai national) and I (white) were separate. If we went through a line at the store and we were both caring something, they would assume we were separate. Same thing would happen at airports and people would send us to separate lines. After having kids, now everyone assumes we are together. Something about the kid – I don’t know if it is looks or the way they interact with us, but now everyone assumes we are family. Oddly enough, if I do walk into a store separately from my family in the town I live, people let me know immediately if my family is in the store.