This is where I am getting conflicting anwers. If you go on
www.univactions.com, there is a spot on the top right hand side to plan your trip (enter dates, number of people etc.).
If you click on "Number of Children (under 18)" this is what it will tell you --
"Enter the number of children traveling on your vacation. Ages 4 through 17 are considered children for your vacation. "
That being said, under 4 years of age do not count.