Q: What about sexuality and emotional attachment. We often here people say you are giving part of yourself away to a person when you have sex with them. Some people can hook up twice a day and feel no attachment while others hook up once and are hung up on that partner for years. Is this something with learn through observation? In what ways does the physical act of sex impact our psychology in regards to attachment?
One word: Oxytocin.
It's a neurotransmitter that's released in the brain post-orgasm. Among other things, oxytocin encourages emotional bonding. Scientists suspect the purpose is to bond a couple throughout the period of child-rearing. Here's a study that discusses the phenomenon:
The neurotransmitter vasopressin may also play an important role, too.
Now my own crackpot theory that's sort of related:
Ever get that incredibly strong "falling in love" feeling? We know that feeling is created by a cocktail of neurotransmitters like dopamine (makes us feel really good), epinepherine/norepinepherine (adrenaline- gives us energy), serotonin (gives us obsessive thoughts about mate), and oxytocin. There's some evidence that we'll have a stronger "falling in love" feeling with people that are genetically dissimilar, and this mechanism is controlled by invisible, imperceptible chemicals called pheromones. All of us give off pheromones, and they carry information about us.
If another person picks up our pheromones and their brain determines they're genetically different (thus increasing the likelihood of producing healthier kids), that "falling in love" cocktail gets released and that person becomes the center of our universe. Since oxytocin is released, we develop an emotional attachment. Our relationship behaviors probably influence oxytocin levels, too, which further enhances the effect.
If we hook up with someone and they're genetically similar to us, we're not likely going to have that release of oxytocin, hence no bonding. There will still be a significant boost in dopamine, which makes the act enjoyable... but there will be no emotional attachment.
There's probably a fair amount of individual variability in the amount of oxytocin released and sensitivity, which is why some people seem to fall in love with pretty much anyone and others never seem to fall in love.