But suppose you're still at it. Do you tell your children you've nicked a few envelopes from the office? If so, how do you react when they tell you they've stolen a packet of cigarettes from one of your friends? And do your children want to know about the real you, anyway?
Now turn the heat up still further. What do you say if you are actively engaged in serious crime? One man who knows better than most is the theatre director Stephen Powell, whose father, Brian, was in and out of prison throughout his adolescence; he has used his father's experience in a new play, Tooled Up.
Spend an hour or two with Brian Powell and you can almost feel yourself being dragged back in time. Dressed in a pinstriped suit, with a brandy in one hand and a cigarette in the other, he holds court in a soft croak, forcing you to enter his world. So instead of being in a trendy West End bar, we might just as well be in some Hoxton spieler in the late Sixties. Which is undoubtedly where Powell would rather be.
Back then, Powell was a face. Not a big one, but a face nonetheless. If there was something dodgy going on, then he was up for it. "I wouldn't describe myself as a professional criminal because I always had a proper job - builder, carpenter, coffin-maker," he says. "I was more of an opportunist. If something tasty occurred, then I didn't say no."
When asked to be more specific, Powell comes over uncharacteristically coy, because it's clear that he has got away with far more than he's ever been convicted for. So instead, he rummages through his mind and mutters something about burglary, chequebooks and travellers' cheque fraud. "Nothing big, mind. Nothing compared to what they're up to in the City," he shrugs.
He abandoned crime after serving his last six-year sentence and expresses relief at not having to look over his shoulder these days, but he admits that life has become a bit - well - dull. "I only used to feel alive when I was up to some skulduggery," he confides. "I used to love going down the pub in a new car, wearing a pounds 200 suit and a gold watch."
Stephen Powell was nine when Brian got his first sentence. "My first inclination was not to tell Stephen anything," says Brian. "So on his first visit, I got my wife to take his glasses off as he walked in the prison so he wouldn't be able to read where he was. When he asked me what I was doing I said I was working on top-secret government business. After they left, I congratulated myself on how well the visit had gone off. But the more I thought about it, the more I realised how badly I'd handled it. I didn't want him told about his dad by someone else; I wanted him to know about me from me."
So on the next visit Brian told his son everything. "I said I was in prison because I had done something wrong, and that he didn't want to end up like me." Which he hasn't, and neither have his brother and sister.
"I did feel a bit ashamed about my dad being inside, and I missed him," says Stephen. "But if I'm honest, I did feel a tinge of excitement about his lifestyle. There was a time when Dad had to keep out of sight, and there were knocks on the door at odd times. The police would turn up unexpectedly and we constantly worried whether the phone was tapped.
"I cottoned on quite quickly that the criminal justice system was a joke," he says. "People like my father never got treated fairly. No one was willing to give him a job when he came out, so in some ways he had no choice but to return to crime."
But what about all those other working-class dads who were in the same boat, but didn't turn to crime and were there for their children? Stephen changes the subject.
"It may sound bizarre, but I think we were brought up with a firm sense of morality," he says. "We were taught the difference between right and wrong, and everything my dad did fitted into an intelligible framework of maintaining a quality of life for the family."
Stephen is aware that this degree of relativism may be unacceptable to many people but, as he points out, the family is still together. His parents are still married and their three children still love them and are interested in their lives.
It's a position that is hard to argue against. Seeing Stephen - the successful director who has transcended his background, worked with the National Theatre and the Royal Opera House, with his father, who is still every inch the slippery, lovable villain - is to witness an enviable intimacy. Neither presumes to know everything about the other's life; nor does he wish to. Both of them just know enough to get on well with one another.
So what is "enough"? Will Mary Bell's daughter's life be improved by the knowledge that her mother killed two children 30 years ago? Clearly a good relationship depends on some emotional honesty and trust, but perhaps the critical question any parent should ask themselves before risking disclosure is this. For whose benefit am I being so open? Mine or my child? This is the minefield that Brian and Stephen Powell successfully negotiated more than 25 years ago.
'Tooled Up' is at the Pleasance Theatre, Edinburgh until 31 August (0131-556 6550)Reuse content