Maybe it would be all right to offer circumcision to a child except for a few things.
The parents might be really overbearing and pushy. If it is something the parents really want they might put unbearable pressure on the child to do it.
The child might be misinformed and be told that if he does not get circumcised he will be dirty, have a smell and be prone to all kinds of infections and problems, which is a lie.
The child might not understand how his fore skin is important for sex. There is case after case of people who decided to get circumcised and called it the worst decision in their life. http://www.circumstitions.com/Resent.html
For these reasons it should be against the law to cut a child before he turns 18.