Like most human behaviour, fetishes are a constant topic of debate in the scientific community. Some are the result of classical conditioning (look up Pavlov's dogs), while others are explained by biology (an asian fetish as described by the OP encourages genetic diversity). Some are rooted more in psychological gratification than anything physical. The best example of this is domination.
However, there are cases that are just disturbing and have no reasonable explanation. Russian serial killer Andrei Chikatilo, aka the Butcher of Rostov, could only have an orgasm if he stabbed his victims. Although he was abused as a child, there`s no record of sexual abuse, which is the usual trigger for such violent kinks and fetishes.
One last note, this may have been said already, but it bears repeating. By definition, a fetish is something that is REQUIRED for an individual to become aroused. If it just help achieve arousal or enhances the experience, it`s defined as a kink. The more you know.
However, there are cases that are just disturbing and have no reasonable explanation. Russian serial killer Andrei Chikatilo, aka the Butcher of Rostov, could only have an orgasm if he stabbed his victims. Although he was abused as a child, there`s no record of sexual abuse, which is the usual trigger for such violent kinks and fetishes.
One last note, this may have been said already, but it bears repeating. By definition, a fetish is something that is REQUIRED for an individual to become aroused. If it just help achieve arousal or enhances the experience, it`s defined as a kink. The more you know.