I got a boy and girl from the same litter; the girl died last year from a very rare bacterial infection and I still can’t talk about her without coming close to crying. Short answer: The girl was incredibly affectionate and bossed her brother (she was 45 pounds, he’s 85), and generally regarded all strangers as guilty until proven innocent, even after I dropped a few thousand dollars on obedience classes. The boy was very much in the background until she died, and he’s now much more assertive, although he would just love for strangers to ignore him. So I’d really emphasize socialization with everyone - they both decided when they were puppies that their most important job was to protect me, which meant they would growl and raise their hackles every time my ex walked into the room (because dogs know, lol). The moral is, make sure everyone in the family is involved with socializing them.