Perhaps, but even they can prove useful. Ours is a war of ideology, something above any mere man. We can't think strictly in terms of territory and resources, which are the causes of most natural wars and conflicts. The war we fight is a continuation of a struggle that has gone on for, quite literally, thousands of years. In the grand scheme of things that isn't particularly long due to how long we last, but the point is that this is a war like no other. These parents and children, given the right prodding, will come to us willingly. We may even find followers among what I'll call "the repentant". Whoremongers, drug addicts, the like. Even they will have their own uses. So, should these parents not leave and their children become mere pawns of our enemy, the parents will be shown what was allowed. Rather than execute them for their lack of discipline, we might recruit them in that they might atone for their sins and potentially even save their child. With the thought of saving their own burned into their minds, they have a good chance of becoming the most dedicated.