I'm one of those terrible people who do not enjoy screaming children at the ballpark. My girls were 9 and 7 before I took them to the park. They had absolutely no interest in watching the games on television or following the team. When my oldest was 12 she made a big show of wanting to go to the park and then by the second inning she looked me square in the eye and said "Ok, we can leave now."
They are 18 and 20 now and LOVE to go to the park. It may take a couple of good reds teams before they'll follow the club on a daily basis, but despite all earlier indications, they are primed to be fans if the local 9 can give them something to root for.