| The sibling relationship is one of the longest relationships in people's lives, and it is also one of the most diverse, as it occurs in many different forms. The current investigation seeks to identify differences in the amount: of social support received in adult sibling relationships. In particular, six different types of sibling relationships were examined in the present study: identical twins, fraternal twins, full biological siblings, half biological siblings, stepsiblings, and adopted siblings. Employing the ideas of natural selection, inclusive fitness, and discriminative parental solicitude, hypotheses were developed about which types of siblings receive the most social support from their siblings. Two general predictions were posited: first, siblings who are genetically related receive more social support than siblings who are not genetically related; second, siblings who are more genetically related to one another receive more social support than siblings who are less genetically related. Results supported both of these predictions, even when social and relational explanations were controlled. |
