Freedom varies. There can be no hard & fast rule, since everything is constantly changing.
We make each decision as it comes, and it's not always easy or obvious. Sometimes it's virtually impossible to know what is right so you make a decision and hold your breath.

Our biggest problem is that she is 12 and he is 9. He thinks he's ready for whatever she's ready for. Sometimes he gets it because she's entitled to it, and sometimes she isn't allowed it because it would be inappropriate for him. In cases of the latter, she must never know. We try to be as honest as possible with them, we always have, but some untruths are good and necessary.

(I am not kidding myself with words like 'untruths', I know they are technically lies, but I do believe there are degrees of duplicity, and not all of it is malicious.)