Why is considered a crime in some U.S. states, isn't that like an exaggeration?

I don't look at it as a matter of birth defects at all. I look at it as a violation of trust and a violation of what is basically right or wrong. And I don't mean from a religious point of view. Children live with their parents and they are in a position of dependency to them, or conversely, the parents are in a position of trust over the children. To have such relations with them violates that position of trust and leave children open to coercion, manipulation and abuse. A child who does not want such contact would feel compelled to give into a parents advances and would not feel secure in either their own body or their personal relationships. Some things are just wrong, religion or birth defects issue aside.