With the abundance of literature focusing on parental influence in sport, it is important to identify family dynamics that extend beyond parents to include siblings. Research indicates that siblings have the potential to influence social, behavioral, and cognitive development across various achievement domains (Brody, 1998). In this study, sibling influence was explored though semi-structured interviews with previously identified elite youth athletes (N=4) and their sibling who participated in the same sport (N=4). Using a grounded theory and retrospective approach, the purpose was to discover how siblings influence elite youth sport participation. After data analysis of the two groups, two main categories emerged from the data: positive experiences participating in the same sport (e.g., growth of sibling relationship, development of understanding between siblings) and negative experiences participating in the same sport (e.g., sibling competition, emotional response). The participants' descriptions coincide with observational learning theory (Mischel, 1966) and both deidentification (Ansbacher & Ansbacher, 1956) and divergence processes (Darwin, 1859; Sulloway, 1996). The data adds to the probable sibling experiences proposed in the Developmental Model of Sport Participation (Fraser-Thomas, Strachan, & Jeffery-Tosoni, 2013) and provides insight and suggestions for athletes, parents, and coaches on how to best manage sibling relations in sport.