Teens are also protected when they do not have access to guns, cigarettes, alcohol and drugs at home. Teens are protected by having parents who have high expectations for school performance.

Add Health measured many dimensions of the home environment. The study asked adolescents about their sense of connectedness to their parents and families: their feelings of closeness to their parents, their satisfaction with family relationships, and their sense of being loved and cared for. Teens answered questions about their participation in activities with their parents, and whether a parent was physically present in the home at key times during the day. They reported whether they had access to guns, cigarettes, alcohol, and drugs a home, and whether their parents expected them to complete high school and college.

Time and time again, the home environment emerges as central in shaping health outcomes for American youth. Controlling for the number of parents in a household, controlling for whether families are rich or poor, controlling for race and ethnicity, children who report feeling connected to a parent are protected against many different kinds of health risks including: emotional distress and suicidal thoughts and attempts; cigarette, alcohol, and marijuana use; violent behavior; and early sexual activity.

When a parent is physically present in the home at key times, and has high expectations for the child's education, children are on the road to being protected from involvement in behaviors that can damage them.

When teenagers have easy access to cigarettes, alcohol, marijuana, or guns at home, parents are increasing the chances that their children will be involved in damaging behaviors.