Too, he lived with them all those years so has learned their ways and think of them as if they're "normal". I still remember the hard time I had always walking too fast for my friends or new acquaintances only to realize it was because my stepmother and brothers always walked fast (and I was always struggling to keep up, walked too slow). We get in other situations and it's heck for us but if everyone stays the same we never learn about differences. You came from outside so you can see them for what they are.

Good for you not over-apologizing for spilling your drink. I think if I'd overheard my father-in-law say that I would have spoken up quite loudly and told him the time I arrived :-) I would have let him squirm a bit internally.