The purpose of the current study was to examine the potential effects of parenting styles and birth order on personality and sibling relationships. Two hundred forty-seven participants completed a demographics questionnaire as well as the Lifespan Sibling Relationship Scale (LSRS) to measure affect, behavior, and cognitions associated with the sibling relationship in both childhood and adulthood. They also completed the Big Five Inventory (BFI) as well as reported on which parenting style their mother and father engaged in while they were growing up. Birth order had no significant effect on any of the aspects of the sibling relationship, but did show differences in conscientiousness and neuroticism. Other significant results were the finding that father's parenting style impact all six areas assessed by the LSRS. Authoritative fathers led to more positivity in assessing the relationship with the sibling the participants felt closest to in their lives. Mother's parenting style affected participants' view of the sibling relationship similarly, but only for adult and child cognitions. Implications of these findings will be discussed, including support for the notion that authoritative parenting results in the most positive outcomes for offspring.