My dad and his siblings were raised knowing OF their mother's Jewish background, but they weren't ever told much of anything about it. Her parents were meticulous about not passing on any cultural or religious knowledge - atheist and communist so I guess it was a matter of principle. Apparently they even used Yiddish as a secret language between the two of them, but didn't teach any of it to their children! When she was older my grandmother became sad about the cultural alienation, but didn't really pass on much of anything besides "you guys are partly Jewish".