A number of myths surround genital mutilations of both boys and girls – so called circumstisions. Science works hard to refute them all – and I do my very best to present the original studies to you right here neat and tidy.
Consequences of genital mutilation (circumcision) corresponds to amputation of limbs
Neurologically speaking, the life-long sexual sensory deprivation which results from circumcision has a profound effect on the neural organization of the brain, similar to that found in any amputee: corresponding neurons associated with states of sexual and emotional ecstasy die, and adjacent neural regions grow chaotically into the dead zone. Furthermore, childhood victims of traumatic abuse tend to have a variety of brain abnormalities, reflecting a generalized rewiring of the brain to adapt to a hostile environment. The psychological impact of such Brain Damage is likely to be Far Reaching.The phenomenon of circumcision serves a practical function of lowering excitability and distractibility quotients-sexual arousal-of pubescent males, i.e. biasing young males toward increased tractability which would enhance group efforts and less toward individual goals of amorous exchanges. Neurological data suggest that early lesions of the Prepuce/foreskin tissues would generate a reorganization/atrophy of the brain circuitry. This re-organization/atrophy, in turn, is suggested to lower sexual excitability. Inferential data support the hypothesis that a practical consequence of circumcision, complementary to any religious-symbolic function, is to make a circumcised male less excitable and distractible, and, hence, more amenable to his group’s authority figures.
Abstract: A Biocultural Analysis of Circumcision. Ronald Immerman, Department of Psychiatry, MetroHealth Medical Centre, Case Western Reserve University, and W.C Mackey. Social Biology 1998, Volume 44, Pages 265-275. 
Circumcision causes life-long harm