Genetic Sexual Attraction

One of the most email articles on BBC today was  Parted-at-birth twins 'married'

I was surprised by the following lines :

Pam Hodgkins, chief executive officer of the charity Adults Affected by Adoption (NORCAP) said there had been previous cases of separated siblings being attracted to each other. "We have a resistance, a very strong incest taboo where we are aware that someone is a biological relative," she said. "But when we are unaware of that relationship, we are naturally drawn to people who are quite similar to ourselves.

Basic googling gave me this on wikipedia : http://en.wikipedia.org/wiki/Genetic_sexual_attraction
Genetic sexual attraction (GSA) is sexual attraction between close relatives, such as brother and sister, who first meet as adults. ^{[citation needed ]} The effect is also seen between cousins. ^{[citation needed]}

2003 Guardian Article on this (Caution : If you feel squeamish about this don't read this. Also extremely long read)

quote: "However, Freud would have had an altogether different take on it, believing that the Oedipus complex was paramount in determining all sexual behaviour. Freud's theory, propounded in 1897, that every male infant has an overwhelming sexual desire for his mother, and every female for her father, is the cornerstone of psychoanalytic theory. He maintained that these incestuous drives were so powerful that they had to be suppressed. Our transition, between the ages of two and five, from the incestuous Oedipal phase to the post-Oedipal phase, resolves these impulses and, according to Freudian theory, is crucial to healthy human development. By the time we reach the post-Oedipal stage, the incest taboo, Freud reasoned, is indelibly imprinted on the psyche, governing future sexual behaviour.

But how persuasive is this Oedipal theory nowadays? Because Freudian ideas dominated much of the 20th century, what is less well known is that, at the turn of the 19th century, a contemporary of Freud's, the Finnish social anthropologist Edward Westermarck, put forward the opposite view, based not on the theory of natural attraction but of natural aversion. According to Westermarck, children growing up in close proximity are not sexually attracted to each other as adults. Quite the contrary: the "Westermarck effect" meant that overfamiliarity and boredom automatically caused siblings and other close relatives raised together to go out of their way to avoid sexual contact. Westermarck also reasoned that, since we find the idea of sex with our relatives so distasteful, we developed moral codes and laws to ensure that society conformed to this "norm" to avoid any social disruption, shame or discrimination."