Arwen’s father is Elrond.
Elrond’s parents were Earendil and Elwing.
Earendil’s parents were Tuor and Idril (Celebrindal).
Idril’s father was Turgon (King of Gondolin).
Turgon’s brother was Fingon.
Fingon was father of Gil-galad.
Turgon’s father was Fingolfin.
Fingolfin’s parents were Finwe and Indis.
Finwe was the Head of the Noldor (2nd branch of the Eldar).
Indis’ father was Ingwe.
Ingwe was the Head of the Vanyar (1st branch of the Eldar).
Finwe’s son with his first wife, Miriel, was Feanor.
Feanor made the Silmarils.
Fingolfin’s brother was Finarfin.
Finarfin’s 5th child and only daughter with Earwen was Galadriel.
Galadriel is Arwen’s 5th cousin.
Earwen’s father was Olwe.
Olwe was the Head of the Teleri after his brother Elwe (Thingol) was left in Beleriand (3rd branch of the Eldar).
Elwe had one daughter with Melian the Maia named Luthien.
Luthien had one son with Beren (Erchamion) named Dior (Thingol’s Heir).
Dior had one daughter with Nimloth named Elwing.
Elwing was the mother of Elrond and Elros.
Earendil’s father was Tuor.
Tuor’s parents were Huor and Rian.
Huor’s brother was Hurin.
Hurin and Morwen had two children: Turin Turambar and Nienor Niniel.
Rian’s father was Belegund.
Morwen’s father was Baragund.
Belegund and Baragund were the sons of Bregolas.
Elwing’s grandfather was Beren.
Beren’s parents were Barahir and Emeldir.
Barahir and Bregolas were the sons of Bregor.
Bregor’s descendent of Beor the Old.
Beor was the Head of The House of Beor (Elf-friends).
Hurin and Huor were the sons of Hareth and Galdor (of Dor-Lomin).
Galdor’s father was Hador (Lorindol).
Hador’s descendent was Marach.
Marach was the Head of The House of Haleth (Elf-friends).
Elrond’s wife was Celebrian.
Celebrian was the daughter of Celeborn and Galadriel.
Arwen is Galadriel’s granddaughter.
Because Tuor was a Man and Idril was an Elf, the Valar gave their grandchildren the option of either race (Earendil and Elwing sail in the skies with one of the Silmarils guarding the Melkor in the Outer Void until the end). Elrond chose to be of the Eldar, but Elros chose to be a man.
Elros fathered the line of the:
Kings of Númenor
Lords of Andunie
Kings of Arnor, and
Chieftans of the Dunedain in direct descent through the Second and Third Ages
At the end of this is Aragorn (King Elessar)
So Arwen and Aragorn are actually related though they are very distant cousins.
Arwen is the 5th cousin and granddaughter of Galadriel.