Circumcision
Circumcision is very important to most branches of Judaism, with over 90% of male adherents having the procedure performed as a religious obligation. The basis for its observance is found in the Torah of the Hebrew Bible, in Genesis chapter 17, in which a covenant of circumcision is made with Abraham and his descendants. Jewish circumcision is part of the "brit milah" ritual, to be performed by a specialist ritual circumciser, a "mohel", on the eighth day of a newborn son's life, with certain exceptions for poor health. Jewish law requires that the circumcision leaves the glans bare when the penis is flaccid. Converts to Conservative and Orthodox Judaism must also be circumcised; those who are already circumcised undergo a symbolic circumcision ritual. Circumcision is not required by Judaism for one to be considered Jewish, but some adherents foresee serious negative spiritual consequences if it is neglected.
Circumcision controversies
The Book of Genesis explains circumcision as a covenant with God given to Abraham, but some scholars reject the historicity of these accounts and look elsewhere for the origin of Jewish circumcision. One explanation, dating from Herodotus, is that the custom was acquired from the Egyptians, possibly during the period of enslavement. A competing hypothesis, based on linguistic/ethnographic work begun in the 19th century, suggests circumcision was a common tribal custom among Semitic tribes (Jews, Arabs, and Phoenicians).