It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: Every child is born upon natural disposition (fitrah), then his parents make him a Jew, Christian, or Magian. It is just like an animal giving birth to a complete animal—do you find any among them born mutilated?
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 7181