Board Thread:Lore Discussion/@comment-82.54.201.244-20150423033615/@comment-4984687-20150425084858

His recounting is merely an underground theory, the general belief is that they were worshippers of Trinimac who were formed by rubbing his ashes on their faces.

Most elven species are descendants of the Aldmer, from Maormer to Bosmer. I'm not sure about Left-handed elves, but Orsimer defenitely are.