My way of seeing things; if I would have been given the choice of who my family was, would I have chosen who I ended up with? Anyone can reproduce (barring medical issues of course), but not everyone should. There is no reason to add stress to you or your family just because you happen to share blood with someone. It's not my place to say whether your reasons are valid or not, but if you can't be happy around them and you know they would be a bad influence on your children, then I'm wondering why blood overrides that. It certainly doesn't in my house. Those who don't add to our lives, aren't a part of our lives. We aren't here a long time; might as well live it as drama free as possible.