Elladan and Elrohir were the identical-looking twin sons of Elrond; older brothers of Arwen. The brothers spent most of their lives as warriors, living with the Northern Dunedain of Arnor; and they traveled with the Dunedain to fight with Aragorn in Pelargir (with the army of the dead), the Battle of Pellenor Fields, and also before the Black Gate.
We are told that Arwen must choose whether to travel with her father or else remain on Middle Earth and become mortal. She chooses to remain, wed Aragorn, and presumably Arwen became mortal when Elrond took ship with Frodo from the Grey Havens - she died (of grief, it is implied) shortly after Aragorn.
We also know that Elladan and Elrohir remained in Middle Earth, and by my reasoning (although Tolkien does not say so) this would mean that they also became mortal.
Arwen had one son and more-than-one daughter with Aragorn; and Tolkien says that this was one of the ways in which the influence of elvishness descended to later Men. I wonder if the same applied to the twins?
Did either or both of Elladan and Elrohir wed a mortal woman, and have children - and therefore (in world) be among the ancestors of modern men?
It would be nice to think so!