Question 1: Do you find parents in the following story as:
a) positive (protagonists)
b) negative (antagonists)

"Dad, why don't I have legs like the rest of the children in my class?"

"It's because it's inherited, dear. As you can see, your mum and I don't have our legs either. Doctors told us that if we reproduce, our child could never walk, but we didn't care about that. Love is what matters and we do love you very much. We don't give a shit about the fact that you and all of your offsprings will struggle for the rest of your lives, but believe us when we say that we love you. We wouldn't let any harm affect you. Except, you know—making you without legs and bestowing all of the other genetic disorders onto you. Love is all that matters!"

Question 2: What is the diference between the following scenarios:
a) Parents do action X, despite knowing that X will cause their child to not have legs.
b) Parents have a baby with healthy legs and do action B to cause it to lose its legs.

Edit: Random info: A whole story sprung up from the content of this comment. If you want, you can read it here.

3334954
As for question one, I would have to say antagonist based on the reasoning. If they had said something to the effect of wanting to share the love and joys of life with a new member of the family despite the risks, then I would say it's about 50/50 at that point.

Question 2
I think the biggest difference would have to be the reasoning behind each of those actions. Also, the cost/benefit analysis would have to be a major factor in it too. As far as differences go, at the absolute fundamental level each of these choices is the same, since they both result in the same consequence. That's how I see it, anyway.

*Edit* After rereading, I would have to amend my first statement to be if they appeared less selfish with the decision, then I would be more sympathetic to the parents instead of thinking of them negatively.

3335076 I agree.