I am apparently of the evil "current wife" breed - aka the Step-Mom. I think that this is not a one answer fits all question. It is totally situational, and no two situations are the same. In our case I can say with absolute certainty that I am a wonderful Step-Mother, and if it weren't for me, my step-son would not know a mothers love. I know we may seem evil to some (biological mothers), but for most, we are a blessing. In our house the BM is little more than an egg donor. I wish she were more, for my son (that's what I call him), but she isn't. I try to pick up her slack and make his life as fulfilled as possible. I am a step-child too, so I know that nobody can replace a "real" parent. But having someone there who loves you can take the sting out of the fact that the "real" parent is not there. I can tell you that the things I do for my son are "real" enough, and in my eyes makes me his "real" parent. I really love him, really study with him, really play with him, really hold him when he is sick. His "real" mother does not. So, which of us is the "real" parent?