Maverick there is nothing wrong with a line bred frog. Like I said siblings and parents breed with each other in the wild too. This is natural and the frogs themselves will do it to further the species. It isn't "Sick" its life. You are looking at it in the perspective like human incest which is not the same. Animals don't see this as morally wrong or disgusting. They see it as a survival tactic.
You are taking a small subject and blowing it out of proportion. You need to find some more material on frog breeding and keeping. Read as much as you can because obviously what we are telling you isn't enough.