But what would it look like to extend some of the special status of adolescents to young people in their 20s? Our uncertainty about this question is reflected in our scattershot approach to markers of adulthood. People can vote at 18, but in some states they don’t age out of foster care until 21. They can join the military at 18, but they can’t drink until 21. They can drive at 16, but they can’t rent a car until 25 without some hefty surcharges. If they are full-time students, the Internal Revenue Service considers them dependents until 24; those without health insurance will soon be able to stay on their parents’ plans even if they’re not in school until age 26, or up to 30 in some states. Parents have no access to their child’s college records if the child is over 18, but parents’ income is taken into account when the child applies for financial aid up to age 24. We seem unable to agree when someone is old enough to take on adult responsibilities. But we’re pretty sure it’s not simply a matter of age.