Validation of the sibling acceptance questionnaire among typically—developing emerging adult siblings of individuals with disabilities

Sibling acceptance is a central component of sibling relationships, including when one sibling has a developmental disability, shaping the quality, stability, and long-term functioning of the family. Despite its importance, sibling acceptance has received little systematic quantitative attention, and validated measures remain scarce. This study validated the Sibling Acceptance Questionnaire among typically-developing emerging adult siblings of individuals with developmental disabilities. The original instrument, developed by Brenner to assess parental acceptance, was adapted for siblings but had not undergone rigorous psychometric evaluation. To do so, data were collected from 854 siblings of individuals with autism spectrum disorder (ASD) or Down syndrome. Exploratory and confirmatory factor analyses supported a three-factor structure: perceived burden and limitation, openness to sharing, and perceptions of parental attention. Internal consistency across factors indicated reliable measurement. Content validity was further supported by significant associations between functional independence and both burden/limitation and openness to sharing, but not parental attention. By establishing the reliability and validity of this instrument, the study addresses a methodological gap and provides researchers and practitioners with a valuable tool for advancing research and interventions that promote sibling relationships, family functioning, and the well being of siblings with and without disabilities.