The Westermarck effect states that children who grew up together or who spent a large part of their childhood together won't find each other sexually attractive.^[1] The effect is named after Edvard Westermarck, a Finnish sociologist. According to Westermark, the idea is to prevent incest or inbreeding. Choosing another partner gives an advantage, so this is not a cultural phenomenon.

This short article can be made longer. You can help Wikipedia by adding to it.