Walk down this thought path with me...
Imagine you are walking down a sidewalk. I fall on you. You have been injured, but you also broke my fall, for which I am grateful.
Now who should be at fault? Me, or the people who threw me off the building?
Now this is a good ethical analogy for non-consensual procreation.
But for an act of consensual procreation, you would have to imagine some twisted logic where I not only fell upon you, but you were also one of the two individuals who threw me off of the building.
Should I be punished for what you did?