I am a step-father of three kids, and have none of my own. My perspective is simple I guess, all kids need love, support, and understanding whether I donated the sperm or not.

A man who does that is an exceptional person.

Probably good upbringing. If you have found a man like that, hang onto him and cherish him. It is not an easy thing to do. My step-dad couldn't do it.

My husband did that ( we don't have kids of our own) and what it says to me is that they are of exceptional character!

Maybe he loves kids or maybe he loves and respects you enough to do what he knows will make you happiest, loving your kids because they are part of you. I wish my husband could do the same for my 2 children, he doesn't cross the line with them but he makes me feel pretty badly quite often and its a constant source of arguments between us.

because for no other reason ...its a kid !

Love and respect for their mother mostly. I would bet he had good parents. You're a lucky girl. Any man can be a father but it takes a good man to be a DAD.

I think a big part of why a man is that way is he realizes that if he loves the girl enopugh the kids are part of the package. You either accept and love them as if they were your own or you treat them like crap and risk losing the woman.

As others have stated, a large part of it is that he loves the mother of the children and wants to do that which will please her. That will include looking after her children. A second aspect of this is that he realizes that the children are innocent victims of the whole situation that caused their parents to no longer be together. Such a man realizes that, whatever happened, whoever was at fault for this situation (if anybody is), the kids have gotten a raw deal and he wants to step in and try to make things better for the children. Such a man wants to do the best that he can to fill the void in the lives of the children that is left by their biological fathers absence all the while know that he can never fully do so. It is not always easy for a man to do this. Such situations can create additional problems in a marriage. Personally, I don't see anything wrong with a man admitting that he is not up to the challenges involved in trying to make a blended family work. However, he should make that decision before he makes a blended family. A real man goes into a blended family knowing that it will not be easy, but committed to doing what it takes to work with his wife to make sure that the children are loved and raised to be loving, responsible adults.