Beren and Luthien are ancestors of both Arwen and Aragorn.

Beren and Luthien's grandson Dior, had a daughter named Elwing. This daughter had two sons: Elrond and Elros. Elrond who chose to be counted as an Eldar (elf) is Arwen's father. Elros, on the other hand, chose to be counted as an Edain (man). He was the first King of Númenor and thus of the Dúnedain. After a long line of kings, Aragorn was born.

A genealogic tree can be found in this Wikipedia page

Beren and Luthien are ancestors of both Arwen and Aragorn.

Beren and Luthien's son Dior, had a daughter named Elwing. This daughter had two sons: Elrond and Elros. Elrond who chose to be counted as an Eldar (elf) is Arwen's father. Elros, on the other hand, chose to be counted as an Edain (man). He was the first King of Númenor and thus of the Dúnedain. After a long line of kings, Aragorn was born.

A genealogic tree can be found in this Wikipedia page