He knows. He lived with then for a few and he even "take care" of Nate and Marshall. Marshall himself said once he was kind of a father even to him. There is even a picture of Nate's dad and Marshall when he was 11/12 years old or something. His name is Fred Samra and he looks a lot like Nate
Didn’t know it lol
+1 answer in: “Nate know who his father? he met him?”