Introductory Psychology CLEP Prep Practice Exam 2026 – The Comprehensive All-in-One Guide to Success!

Individuals who share more genetic material with one another are more likely to have the same adaptive traits, making them more likely to survive and reproduce. This is known as kin selection. Same-sex siblings share roughly 50% of their DNA, thus forming a kin bond would increase the likelihood of survival for both individuals. Option A, parental bonds, may also provide an evolutionary advantage, but this is not specifically mentioned in the question. Option B, stress bonds, have no known evolutionary advantage and may even be detrimental. Option D, romantic bonds, do not necessarily involve shared genetics and therefore do not have an evolutionary advantage in the same way that kin bonds do. Overall, the observed similarity between same-sex siblings suggests that it is an evolutionary advantage for an individual to form bonds with those who share a significant amount of genetic material.