When young children grow up together they become desensitized to later sexual attraction. This is called the Westermark effect after Finnish anthropologist Edvard Westermarck. This occurs whether or not the children are related. It’s why people can be as repulsed by the thought of being with their step-siblings as they are with blood relatives. When children grow up away from family members this effect never occurs and for some reason there is often an extremely powerful sexual attraction if they meet later in life as adults. It is powerful enough that many act on it knowing exactly what they are doing. This happens between siblings, half-siblings, mother and son, father and daughter, and reportedly even between members of the same sex. People destroy their own relationships, families, and careers to be with someone society doesn’t allow them to be with. In most of the stories I’ve read or heard, the sexual relationship doesn’t last, but there are some couples who insist on being together no matter the cost.
It sounds crazy, but when you hear people who’ve been through this describe what happend, you know there’s something to it. If you have about 37 minutes to spare, check out this link to a CBC radio program. Listen to part 2 and the first part of part 3. The woman being interviewed, Aziza Sindhu, replays interviews from 2 cases.
To the best of my knowlegde, I don’t have any close relatives that I didn’t know as a child, so I don’t think I have to worry about this, but I know someone who does.
Brother and Sister, and Lovers – ABC News
The Brother and Sister Who Fell in Love – buzzle.com – a sibling couple with 4 children together, determined to stay together
Forbidden Love Between Siblings – ABC News again – another couple determined to stay together
Parted-at-Birth twins ‘married’ – BBC News – These two didn’t know they were siblings when they got married. The story brings up the idea that it’s important for adopted to children to know about their birth parents so that this doesn’t happen. However, most of these relationships occur when relatives seek each other out and wouldn’t happen if this information was never available.