I could be wrong, but I don't think Aragorn had any Elven uncles. His father-in-law, and thus his wife, are both Elves, but Aragorn's Elvish ancestry goes way, way back to the first King of Numenor, Elros Tar-Minyatur, who is Elrond's brother, yes, but that means his great-great-great-great-great-great-great-throw-in-a-few-dozen-more-greats uncle is an elf, not an uncle. Elros became mortal, though, his progeny are all 100% human, regardless of what that super-great uncle Elrond is.