Usually, yes. To begin with, most "child actors" are older than they appear on film and may not be minors (less than 18 years of age). While a 10-year old person is obviously quite young, it is easy to find an actor who is 18 or older to play the role of someone who is 15 or 16. In addition, with the judicious application of a little makeup, it is much easier to make an older person look realistically younger than it is to make a younger person look older. It is also much cheaper and easier to have a person smoke a cigarette than simulating it through special effects, which limit the ability of the film crew to take certain shots (e.g., if a tube is used to emit smoke, the actor must be positioned so that it does not show on camera). Actors do not need to inhale the smoke into their lungs to appear as if they are smoking. They need only to hold it in their mouths, before exhaling through the mouth or nose, to create the appearance of smoking. They may be shot holding a cigarette, while not actually showing them put it into their mouths. Even if it is shown in their mouths, they do not necessarily inhale. Watch closely and you will notice that few 'smokers' actually inhale on camera. Finally, some of these "child actors" certainly smoke themselves and are no stranger to tobacco or other burning bushes (a-hem). The past couple of decades has seen a significant shift in the portrayal of smoking in films and television, although smoking was uncommon on television sets for technical reasons. The production companies and studios are subjected to pressure from groups who consider any portrayal of smoking a 'glamourization' of a dubious habit and encourages young people to smoke. Although smoke-filled and moodily-lit rooms set a tone in past dramas, they are now considered inappropriate. Only the bad guys smoke these days.