Depends on the parenting style I suppose. My brother started properly watching Football around the 98 world cup, so with the buzz around Michael Owen and the Argentina goal, that swung it for him and he was a red. Me and my Dad being blues didn't really make much of a difference, if you tell kids not to do something, sometimes they'll want to do it all the more.
At the end of the day, it's a rivalry. Controversial opinion but I don't think, as a people, Liverpool fans are any worse than any other set of fans. The reason for this is, I don’t think the Football club a person chooses to follow necessarily defines them as a person. I don’t believe it’s an associated ideology. I never grew up thinking United fans were better than others because they got success and we all didn’t. It was just the luck of the draw, and as we’ve already covered, most don’t even “choose” their Football club it’s just a loose affinity normally assigned by family at an early age.
Liverpool have got their far share of bells and they've got decent folk too who have followed them all their life. With success, the global number typically increases, which then prompts the conversation about whether these fans are somehow 'lesser' than local fans.
More importantly, it prompts the even bigger conversation about 'what success does to people'. City and Chelsea now arguably have a higher proportion of bells following them than they did 20 years ago for obvious reasons. When you win the lottery, you have people like Michael Carroll and you have those who become lovely, charitable people who just enjoy their new found lives.
'Nowt as queer as folk'.