Well, (and this is just based on my understanding of how things went down) she was formed from Sora's soul and body, and Kairi's heart. So, kinda? But not really. But kinda? It depends on your definition of parents and children. She's definitely not their child in the traditional or genetic sense, but if your definition of child was "someone formed from and having the characteristics of two different people" or something like that, then maybe. I definitely don't see this way of looking at it being explored in-canon though, nor do I see Sora and Kairi filling those roles for Namine. If you like the idea though that's totally fine to think of it that way, it's an interesting take on it.
Edit: Oh okay lol, you had me there for a minute! But man, that would be one dysfunctional family... (shudders)
NaminÃ¨'s existence is confusing because she's an anomaly. Diz placed her in the category of a Nobody because there was nothing else to make sense of her. I honestly feel she's a sub species.
Sora just acted as a catalyst/intermediate because Kairi's body and soul weren't there. But she has nothing belonging to Sora himself, which is why she did not return to him. She's Kairi's shadow in the truest sense of the word.
So, uh, yes and no?
Does this mean Roxas has two daddies (Sora and Ventus)?