Like good, modern parents we carefully limit the amount of television our children see. With the exception of the occasional Scooby Doo marathon (I still argue it is educational) television is doled out my children in minute doses - the way most parents regulate candy or cookies.
Consequently, following the proven maxims of the economics of childhood, scarcity leads to jealousy. This explains why when I picked my daughter up from daycare the other day, but without her brother in tow, she looked at me suspiciously and asked: "Where's my brother? What's he watching?"