Familism, sibling relationship qualities, and sibling sex constellation as predictors of alcohol use among Mexican-origin adolescents.

Sibling relationship qualities and traditional family values (i.e., familism) are contextual factors relevant for early substance use risk among Mexican-origin adolescents. Yet limited research has examined whether familism moderates the effects of sibling relationship features on alcohol use. The present study examined whether familism enhanced or reduced the effects of sibling intimacy, negativity, and sibling deviance on later alcohol use, also testing whether sibling sex constellation (sisters, brothers, mixed) modified the patterns of influence. We analyzed two waves of data ( N = 404) from the California Families Project, a longitudinal study of Mexican-origin youth. Using zero-inflated Poisson models, we examined unique and intersecting prospective influences of age 14 sibling contexts and familism on the likelihood of and degree of engagement in alcohol use at age 16. Results indicated a complex interplay of sibling features, familism values, and alcohol use patterns. Familism moderated the effects of sibling intimacy on later alcohol use patterns. For those with lower familism, increasing intimacy was associated with higher probability of any use, but decreasing degree of use (especially for brother pairs and sister pairs). Among those with higher familism, increasing intimacy predicted reduced probability of any use, but increases in the degree of use (for sister and mixed pairs). More sibling negativity was related to reduced alcohol use probability for brothers, and increased alcohol use in mixed sibling pairs. Sibling deviance was associated with greater age 16 alcohol use. This study highlights cultural considerations for including siblings in substance use prevention programs for Mexican-origin youth. (PsycINFO Database Record (c) 2019 APA, all rights reserved).