Pretty much nicked from Steven Pinker's 'How the Mind Works'. Just trying to understand what he said by explaining it to myself:
One of the most important and influential memes of the twentieth century was Freud's idea of the Oedipal Complex.
This boils down to thinking that a lot of what we do as adults is down to the desire of a boy to fuck his mother, which is then repressed, leading to all sorts of weirdness.
Repression is a technical term meaning "If you deny you're feeling this, then that just proves you are. Nyahh, nyahh".
In the 'hydraulic theory of the mind', unreleased pressure can build up until it explodes. This theory is so deeply embedded in folk wisdom now that we use phrases like 'letting off steam', 'releasing the pressure', and 'throttling up to try to make Crewe by 16:53' almost without thinking.
One weird thing about this theory of the Oedipus Complex, that perhaps should have alerted people to difficulties, is that virtually all males find it ridiculous.
I trust that my mother will not be offended if I say that, although I can appreciate that she is a beautiful woman, and that in her thirties, when I was becoming a sexual being, she must have been hot indeed, I have never felt the slightest desire to knock her off.
Given my otherwise fairly omnivorous teenage lust, this is a strange datum that needs explaining all on its own.
The answer may be something called the Westermarck Effect. It's been suggested that people have an aversion to those they were reared with. Presumably the reason for this is somewhere in evolutionary biology.
If that's true, then it actually explains why Freud took his theory seriously.
Freud and his patients were wealthy Austrians. The custom of the time was for that class to have their children raised by wet-nurses and nannies. Without the childhood proximity to activate the Westermark effect, Freud and his patients would have found their own mothers as attractive as any other women.