The lessons of relationship that our primordial ancestors learned are deeply encoded in the genetics of our neurobiological circuits of love. They are present from the moment we are born and activated at puberty by the cocktail of neurochemicals. It’s an elegant synchronized system. At first our brain weighs a potential partner, and if the person fits our ancestral wish list, we get a spike in the release of sex chemicals that makes us dizzy with a rush of unavoidable infatuation. It’s the first step down the primeval path of pair-bonding.