The courts, in my never-to-be-humble opinion, place WAAAAAAY too much emphasis on a matter of biology. In darker cases than this, it's resulted in children going back to abusive households to be abused again or even killed.
There was a recently a case in the news here where two children were killed and a third was left in critical condition -- "mom" had left them in a hot car, but apparently moved the bodies inside before calling for help. Social services had visited the home over 20 times in the past year.
However... I suspect in this case, the courts will not be involved.
"Well, yes, your Honor, he and I do have identical DNA (and those strange bits the lab noticed are the Kryptonian parts) but that's just because he's from an alternate reality... hey, who are those guys wearing the white coats?"
PJ
who really shouldn't be joining this argument as she hasn't read any of Kidnapped
-- too traumatized by the subject matter to read this one in installments!