Sibling group cohesion : a definition, validation, and power in predicting perceived personal achievement

The goals of this study are to describe the importance of developing a measure of sibling group cohesion, to define this measure, to test the validity of the measure using similar constructs, and to explore how sibling group cohesion predicts perceived personal achievement. Sibling group cohesion is defined as an individual’s voluntary commitment to one’s group of siblings, which forms an open unit. A 12-item scale of adult sibling group cohesion is developed and validated. Adult siblings from sibling groups of 3 or more were asked to take an online survey and 541 participants from 184 families completed the survey. Three theories are proposed for how sibling group cohesion could impact achievement: support, expectations, and shared identity theories. Results indicate that sibling group cohesion is related to, but still unique from, the average and standard deviation of dyadic sibling relationship positivity quality. Individuals from larger families, who have a high proportion of siblings who inspire them, and who have high and consistently positive dyadic relationships report having high sibling group cohesion. Additionally, results from this study show sibling group cohesion is a strong positive predictor of two measurements of perceived personal achievement. The predictive power of sibling group cohesion is stronger than that of the average of dyadic sibling relationship positivity, and is mediated by a combination of support, average dyadic positivity, and demographic variables. Specifically, receiving active and emotional support, as well as being introduced to activities by a majority of one’s siblings is predictive of better achievement.