First of all, we should start from the point that sort of 90% of 'donors' are involuntary in this kind of stories: their clones are, so to speak, fruit of a violation. Of course this doesn't mean clones don't deserve care and affection, I'm just saying that most of the times their 'parents' don't even know they exist, nor they've had offsprings of their own free will. That's part of the 'loneliness of the clone'.
This could be the rightest answer overall.
This, too. For example:
Longshot/Shatterstar is one of the most warped cases. Both are fathers, both are children, are they siblings, or none of it? How could we say that one of them is responsible of the other one? (Well...I guess Longshot IS responsible of 'Star, since he 'built' him with Alison...though I pretty much doubt he had the slightest idea about procreation, I pretty much doubt he could be really fertile, and up to today I still don't understand why Ali didn't took precautions).