Like many American parents, Matt and Amy Roloff balance the soccer practices, driving lessons and studies of their four children and try to spend time with each other. Unlike many families, Matt and Amy are faced with an additional challenge every day of their lives—they are little people.

Since the debut of their hit TLC reality series, Little People, Big World, America has fallen in love with Matt, Amy and their kids, Jeremy, Zach, Molly and Jacob.

There are 200 different types of dwarfism, and Matt was born with what's called diastrophic dwarfism. "It comes with a lot of cartilage and joint deformities, and so my hips and my knees and my fingers don't work properly," he says. "Our heads are well proportioned, but we all have funny-looking hands and legs that aren't straight, typically, but we're very capable and usually most diastrophics have good ability to adapt."

Amy, who was born with achondroplasia dwarfism—the most common form of short-limbed dwarfism—says becoming a mom was always her biggest dream. "Most people may assume that little people will have dwarf babies. That's not always the case," she says.

In fact, three of the four Roloff kids are average size. Twins Jeremy and Zach are the oldest Roloffs, but they aren't identical. At 17, Jeremy is almost two feet taller than Zach, who is a little person like his parents.