Yeah there's no actual dividing lines or areas of reds and blues or anything like that. I know plenty of siblings who support different teams.
Evertonians will tell you, though, that the majority of Scousers are Blues. It's utter bullshit. There's well more Reds.
What is interesting, though, is that most of the Blues I know do seem to "go the game" and have season tickets. So either some of them are lying and there's a fanbase-wide conspiracy to make out like they all attend the games and are superfans, or Goodison is actually a magical portal that appears to only have a capacity of 40,000, but actually holds many, many more.