"Have you ever tried drugs, Mum?"
Now there's a teenager's question to strike terror into the heart of many a parent who dabbled with substances they'd really rather not have in their youth.
For years you have told them that drugs are an evil not to be messed with and they go and ask if you ever experimented.
What are you supposed to say? If you have always lived a life of abstinence then it's a no-brainer, telling them truthfully that you wouldn't ever do such a thing.
Or if you have overcome a drug habit in the past, battling back to health to have your family, you may also have a firm answer in mind – letting your kids know about your mistakes and alerting them of lessons learned.
But what of the millions of us in the middle ground – those who perhaps smoked the odd spliff when they were younger or say, briefly took magic mushrooms?
I've found myself in exactly this dilemma and have chosen to airbrush my past – for now at least. There are certain things my girls don't need to know about me.
And it's not just the thorny issue of drugs that throws up such concerns.
I can't be the only mum who is gearing up to lie to their children about the age they lost their virginity, how much they drank or how much sex they had in the past - at the age of 14 my daughters really don't need to know, do they, even if such questions are starting to crop up.
And it seems I won't be the only one glossing over a past I'm not too proud of.
Melissa Hood, head of training at the London-based Parent Practice which offers a range of courses and resources for families, confirms it's common place for parents to admit to worrying about fessing up to less than perfect behaviour to their children.
She says: "Parents need to ask themselves why they are worried. Did they have a negative outcome that they now regret from their own behaviour? Or did they come through it alright but think they were lucky to do so and their child might not be so fortunate?
"Or do they think that what kids are exposed to these days is somehow different – for example, is marijuana much stronger than what was available in the past?
"Or do we have more information available now about the effects of the risk-taking behaviours we indulged in, such as the effects of alcohol or soft drugs on the brain?
"Only when we've answered these questions honestly to ourselves can we have any credibility when speaking to our kids."
Melissa skilfully identifies my own misgivings about discussing such potentially taboo matters.
"Whether this is the result depends partly on the nature of the communication between parent and child and partly on the behaviour being modelled currently," she says.
"Young people are more likely to listen to and to trust the parent who listens without judgment to them and who has a history of welcoming the child's opinion.
"If there is this relationship of trust then the child is likely to pay attention if the parent says what the behaviour was and that they regret it now and gives reasons.
"A parent often needs to spell out that it is their role to keep the child safe and that they have knowledge and experience which puts them in a better position (now that they are adult) to make decisions than the child. The decision making part of the brain is not fully mature until well into the 20s.
"Some things are safe to do when the young person has the maturity to make the decision for themselves.
My friend Isobel, mum to William, seven, is also pondering what to do for the best – when the time comes.
"My approach before I had children was pretty selfish – and why not?! I only had myself to please, plenty of disposable income and lots of friends to party with! I didn't actively go out and seek drugs but if they were available at a party or club, I'd join in with friends. Nights out would quite often be very drunken and always pretty raucous.
"Becoming a mum was such a sea change in everything – it knocked off my selfish edges, and was all-consuming for a long-time. I was too tired to go out partying, and my whole focus changed, from just me, or me and my partner, to our family. I began to want different things, and get pleasure from much simpler things – I'd rather be spending time with my family than out drinking and socialising. I don't necessarily regret things I've done in the past, but I won't be boasting about them to my son either.
"My son's not at an age yet where I'd be talking about these things - I hope the way I'm bringing him up is to talk to me, openly and honestly about things, and I'd hope to use my experiences to help guide him, when the time's right. If that's to guide him away from doing something then that's fine too.
Isobel has some thoughtful guidance on how she will speak to her son.
"I feel I did things sometimes to be part of the gang, and what I'd want to share with my son is be your own person. Ensure you trust the people you are with, and trust your instincts. Don't get bullied by peer pressure to do things you don't want to.
Melissa Hood offers more sound advice.
She says: "It is healthier for many reasons that children should see that parents can make mistakes and also that they clean up after their mistakes.
"Making mistakes doesn't mean that the parent can't still be the figure of support that the child needs and a person to turn to for advice."
Phew. I couldn't be happier to hear it.
More on Parentdish: Surviving Teenagers: Talking about drugs