Adolescent wellbeing is associated with positive outcomes in early adulthood in a sibling comparison study

Puberty through adulthood involves major psychological and social change. Prospective evidence on adolescent wellbeing and later outcomes remains limited. Here we show that higher adolescent wellbeing (age 14-16) is associated with more favourable psychological and health-related outcomes in early adulthood (ages 20-25 and 25-35). Using data of 14,518 twins and siblings of the Netherlands Twin Register, we examine associations between adolescent wellbeing and adult wellbeing, flourishing, personality traits, self-rated health, and sleep quality using both between-family and within-family designs. Between-family analyses indicate positive associations with early adulthood wellbeing (β = 0.32;0.38), flourishing (β = 0.27;0.34), conscientiousness (β = 0.18;0.22), self-rated health (β = 0.09;0.18), and sleep quality (β = 0.59;0.87), and inverse associations with early adulthood neuroticism (β = -0.34;-0.11)(pFDR<0.05). Associations with self-rated health (β = 0.09), sleep quality (β = 059;0.66), and neuroticism (β = -0.11;-0.37), remain significant (pFDR<0.05) after adjusting for adolescent levels of the corresponding outcome. In the within-family analyses, that control for shared familial factors, associations with wellbeing (β_20-25 = 0.12), flourishing (β_20-25 = 0.17), self-rated health (β_20-25 = 0.07), sleep quality (β = 0.46;0.71), and neuroticism (β_20-25 = -0.12) (pFDR<0.05) were also observed. The findings characterize long-term associations between adolescent wellbeing and early adulthood outcomes, with attenuation observed after accounting for shared familial factors.