In fact, if the surgery is not actually therapeutic, it can be seriously argued that it might be considered mutilation, even though it produced cosmetically preferred external genitalia.
Ordinarily, the human body is not to be cut and rearranged, except for theraeutic reasons, and (of course) with consent.
That is correct as far as it goes. However, the social pressure for sexual conformity within a religious community and/or socialization as an adolescent and an adult has very strongly motivated the medical community to counsel parents to grant permission for life altering surgeries, drugs, and other treatments in an effort to make the sexual presentation conform to some arbitrary decision. This social pressure varies in different cultural settings. The Batista family lived in a cultural setting where the social pressure permitted the affected children to adapt to their circumstances and participate in their church and other social activities without a shame that destroys their mental health and life. In other cultures, the shame imposed upon the child an dthe child’s family by social pressure tends to motivate a medical intervention. In some Ancient Greek cultures such as Sparta, such childdren were simply killed outright, often by exposure to the elements and scavengers.
See:
What’s wrong with the way intersex has traditionally been treated?
http://www.isna.org/faq/concealment
Also see:
Who was David Reimer (also, sadly, known as “John/Joan”)?
http://www.isna.org/faq/reimer