Familiar faces, familiar spaces: Social similarity and co-presence in non-relational behavioral convergence

Social influence is frequently measured through an ego's direct ties. Although influence may also stem from an ego's indirect ties, reference group, and casual contacts, it is difficult to capture their impact using existing network methods. We identify and trace the influence stemming from an ego's “familiar others,†consisting of those socially similar individuals with whom the ego comes in contact at school, but does not necessarily share a relationship. To evaluate the role of familiar others, we investigate unhealthy weight behaviors in adolescence using data from the National Longitudinal Study of Adolescent to Adult Health. Our results demonstrate that familiar others' unhealthy weight-related behaviors are strong predictors of the ego's own weight behaviors, net of immediate alters' behaviors, and individual-level characteristics. Further, we find that this relationship is stronger and more robust than that between egos and their direct ties. These results suggest that familiar others constitute a key source of social influence that is distinct from the influence of network alters.