Well, yeah. I mean, if it was his blood-related uncle, then he could tell him about his parents, who they were, show him some photographs. The memories the MC told Mila or Vic seem very vague, just like in your own example. He was no more than three years old when he may have seen his mother, so it is unlikely that he remembers any details.
"European cultures, well everyone with a beard can be an uncle."
Do you mean that a teenager can call his parents' neighbor friends aunt and uncle even though they are not blood relatives?
Or is he an uncle in the same sense as Uncle Ruckus?