Where does the desire come from?
While there are many theories about the origin of the BIID desire, no one knows for sure. Some people suggest it is a congenital disorder, others argue it is something acquired later in life (albeit relatively early in life). Some people say it is a mental illness, others argue it is a neurological disorder. Ideas as wild as "unresolved issues from a past life" have even been put forward. Some other people state it is simply a lifestyle choice or a desire for body modification (both theories with which we disagree).
The fact is, we do not know where it comes from. We are also unlikely to know for sure what the origin of this unusual desire is.
We posit that knowing the origin of the condition is not as important as providing relief from the condition to those who seek relief, and that surgery may be the only viable treatment option until a less invasive way is found.
In the particular case of limb amputation BIID, as recently as November 2006, Ramachandran and McGeoch hypothesised that it is to do with the body's image of itself as is located on the right parietal cortex of the brain. This in turn suggests a mechanism to explain the preference for left limb amputations that appears amongst those who use the internet chat groups. As yet there is no such 'mechanism' hypothesised for other BIID manifestations - deafness, blindness, paraplegia etc. See Can vestibular caloric stimulation be used to treat apotemnophilia?
