Migraine disease doesn't discriminate by age. Very young children can get Migraines as can the elderly.
Some children will experience their first Migraine before they're old enough to talk and tell their parents what's wrong. When talking with their doctors, it's important for parents to tell the doctor if there's a history of Migraine in their families. This can help a great deal with diagnosis.
People are often told they'll "outgrow" their Migraines. Women are often told they'll stop after menopause. While both of these statements hold true for some people, they're not true for everyone.