How about the truth? Don't sugarcoat it for them because they will grow up and figure it out themselves and then they will resent you for gaslighting them. The truth is that in making the decision to not parent one's own child, it is just as much to seek a better life for THEM as it is for us. And I'm not sure what the statement "adoptive mothers are doing the best they can" is supposed to imply here. Are all of them? What about the ones who abuse and murder their children? What about the ones who return their children like the Stauffers? These are not anomalies. You might be doing the best you can at parenting right now, but that does not make adoption some happy wonderful thing we should all gush over. Doing the best you can, in my opinion, would mean recognizing that your children have trauma, that they will likely grow up feeling like they are never enough, that even if they don't say it, they are deeply sad in a way they cannot even articulate. Doing the best you can means sitting with your frustration and recognizing that you brought most of it on yourself by participating in a system that is far more unethical than it is touted to be. Sit with that and be honest with your children, and do what my adoptive parents did: apologize to them.