But I think the impression kids get from being asked that question a lot is that they ought to know from a very young age what they want to be. The answers are usually quite predictable - doctor, teacher, scientist, musician, teacher, etc - essentially based on what the kids enjoy and think the occupation will allow them to do. Lesley-Anne has been vacillating between a vet and a dancer for the longest time. Andre is more fickle, with aspirations that have included a truck driver, a fire fighter, a badminton player, a chef and the latest one - a computer games developer (I approve of the last one, especially since he has promised me free games!)

If you ask me, I would say it's not important at all for kids to know what they want to be when they grow up. It's more important to expose them to as many experiences as possible, so that they may form their own preferences and opinions about what they enjoy doing. Armed with knowledge and information, they will be able to make wiser choices about their careers. There's plenty of time for that.
Incidentally, don't you think it's interesting that kids always choose an occupation where their passion lies, whereas adults often don't? Somewhere along the line, passion takes a back seat to other considerations like money and status, so much so that it sometimes becomes totally disregarded. I'm not suggesting you can throw pragmatics out the window, that would be unrealistic. But since we're discussing practicality, I'm sure many of you would agree that you won't be very happy or motivated in a job that you have absolutely no interest in, no matter how much it pays you.
Following this argument, I feel that too many parents hijack their children’s dreams for "pragmatic" reasons. I have a friend who became a doctor because her parents were doctors and practically forced her into medical school, even though she desperately wanted to be a lawyer. Being the only child, she dutifully followed her parents' wishes and became a doctor, but I feel so sorry for her that she has been denied the chance to forge her own path.
To me, as long as the chosen profession is legal, ethical and realistic, we parents should respect it. When I say realistic, I mean choosing it for the right reasons. (At one point, Andre wanted to be a police officer because he thought it might be cool to carry a gun. No, no, no.) As much as we may be disappointed with our children's choices, we need to recognise that they are their own individuals, not projections of us. That's not to say we can't guide them in their choices, but it's not fair to ask them to live our dreams at the expense of their own.
So my advice to my kids? You can be anything you want, as long as you work at it. And you don't even have to know what it is yet.