Yes, neurotypicals are indeed able to have large family dinners. But they have to do it using table manners as a crutch. They can’t just have an honest conversation about what’s really necessary, they need to rely on this social construct to tell people what to do without explaining why. It’s a great weakness. If only the average person weren’t so afraid to introspect and to question why we do things.
OP (dad), married a woman and accepted her daughter into the family, making her his stepdaughter. We’ll call her Drake. Dad already had a son from a previous marriage. We’ll call the son Josh. Drake and Josh became close stepsiblings. Drake started dating a boy, who we’ll call Freddy. Drake introduced Freddy to Josh, and they hang out every week at Josh’s place to play Overwatch. Drake brought Freddy to her house, where dad was cleaning his guns, just in time for Freddy to walk past on his way to Josh’s room.