Gnat problem? Fruit storage?? HELP!!!?

I've learned gnats are attracted to fruit & We keep a bowl of apples, bananas and oranges on the counter. I never see gnats around the fruit bowl, but I will always see no more than one or two that appear when I'm eating at the dinner table. How can I prevent gnats in the house? And how else should I store my fruit? Its gotten to the point where I'll see one upstairs in my room or in my bathroom. I could understand if it was summer, but its 30 degrees outside and gnats aren't around. Any advice?

Oh also we have a plant in every room (I don't know if that has anything to do with it either but I never see gnats in there either)