Obviously the solution to determining Selkie’s biological father is Sarnothi Maury Povich.

↓ Transcript
Todd: Through circumstances I won’t bore you with the details of, I thought that kid didn’t “make it”. I found out that was wrong just last November.

Todd: We’ve been working on building a relationship with each other, but I still can’t help thinking about all the time we COULD have had together, but didn’t.

Todd: And please let me be clear. I can’t, and WON’T, acknowledge you to Selkie as being her father.

Todd: There’s just simply no way to prove that to be the case. Her father could be someone from after, or even BEFORE, Plo Quar knew you.

Todd: However. I feel like you’re trying, genuinely, to make amends for your past.

Todd: So I will talk to Selkie, and see if she’s willing to interact with you as a “family friend” only. But it’s HER decision. Fair?

Scar: Thank you. Is more than I am deserving.

Paternity tests are probably a thing they could pursue, but I can't see Todd putting Selkie through that based solely on conjecture.