Aragorn and Arwen Are NOT RELATED

[Ibrîniðilpathânezel]

The most detailed genealogical breakdown of any character that I have seen is in the Encyclopedia of Arda's for Elrond, in the first footnote:

Though he is known as 'Half-elven', Elrond's lineage is much more complicated than that title suggests. He could claim descent from all the main branches of the Eldar, each of the Three Houses of the Edain, and even from the Maiar. To be completely correct, he was slightly more than half-elven: actually nine sixteenths of his ancestors were Elves. A full breakdown of his descent works out like this:

Three eighths Edain, through two lines: his grandfather Tuor of the House of Hador, and his great-grandfather Beren of the House of Bëor. He was also descended from the third House of the Edain, the Haladin, through Tuor's grandmother Hareth.

Five sixteenths Sindar, again through two lines: his grandmother Nimloth and his great-great-grandfather Thingol.

Five thirty-seconds Vanyar, through his great-grandmother Elenwë, and also through his great-great-great-grandmother, Indis the second wife of Finwë.

Three thirty-seconds Noldor, through his great-grandfather, Turgon (who himself had only three-quarters Noldorin blood).

One sixteenth Maiar, through his great-great-grandmother Melian.

Obviously, the same would hold true for Elros, despite his choice to become mortal. As genealogy is usually traced to the nearest common ancestors, for Aragorn and Arwen, it would be, as has been said, Eärendil and Elwing. Being full brothers, Elrond and Elros would have identical lineage, but beyond that point, the lines drift apart. By the time of Aragorn's birth, the drift is continental in scale and the consanguinity is so dilute, it would take an immortal Elf to even think of them as kin. But they are related — incredibly distantly, but related nonetheless.