I think the parent is just pointing out that the outrage seems a bit disproportionate. There are far more damaging things a parent can do that most people accept, whereas the actual effect circumcision has on your life is basically zero.
Passing on genes, well we generally don't want to prevent that, because, contrary to forbidding circumcision, the cure would be worse than the disease.
That's the part when you introduce your values and your judgement and try to make it sound as if everybody agrees.