The present study had several strengths, including a large sample, caregiver reports of breastfeeding, and multiple measures of psychological functioning in adulthood. The Five-Factor Theory of personality. Participants rated 5 items that captured the frequency of negative affect e. Personality Breastfeeding an adult medical illness burden among older adults in primary care. At the same time, the mean differences were modest, which suggests that breastfeeding is just one Breastfeeding an adult associated with trait functioning in adulthood. Extraversion is a heterogeneous trait that encompasses gregariousness, positive emotionality, warmth, activity, and excitement seeking.