This is for sure. I do not know the number of studies that support this fact, but it must be impressive. More and more studies are being added, such as this one from Izmir, Turkey: Infections of the lower respiratory tract are nearly five-fold increased in children with smoking parents, compared to children growing up in a smoke-free home.
Studies that fail to show an effect of passive smoking are often faulty. In Rome, Italy, researchers have spotted the fault, and after it has been removed, the real result showed up: Parents who smoke at home make the lung function of their offspring drop. A first negative result has been due to the passive smoke exposition of some children not at home, but outside, clouding the difference between smoking and non-smoking homes. If ever you hear of a study claiming no effect, keep this example in mind.