Before I start talking about half-elves again, I’m going to give the disclaimer that the connection made is probably a stretch but it's just an idea about a fantasy world. Also, warning: a few little spoilers.
My world view of Thedas and other cultures absorbing elven culture and perhaps genetics changed over two words spoken in Inquisition – easily missed if I hadn’t been listening, or if I hadn’t had the right people in my party at the right time.
-The first perspective changing word, spoken by Solas a foiled attempt to speak the elven language to Sera, was “fenedhis”. I attempted to look up the meaning and from what I gather from others’ opinions, Solas was basically using profanity and telling Sera to suck his dangly bit.
-The second perspective changing word, shouted by Dorian in a moment of stress, was “vhenedis”. So I attempted to look that up, confirmed that I heard right by finding the word “vhenedis” on a list of Tevene (the language of Tevinter) words. It is listed as a curse word – profanity. Perhaps Dorian was referring to his junk.
Now, maybe I’m reading too much into this tiny little thing – the Elven and Tevinter curse words that are so close that they may be indistinguishable when spoken quickly - but I had my share of linguistics courses in college and I learned that when two cultures share intimate parts of language, it usually means that they share other intimate things – perhaps even genetics. I don’t think this is a case of lazy writers reusing a word and just changing the spelling a bit. I think the similarity between these intimate words is intentional. With the Elven and Tevinter cultures reaching back in time to the fall of Arlathan, Dorian’s comments on “careful breeding” to maintain magic in the bloodlines of Tevinter’s noble families, Abelas’ revelation that the elves had nearly done themselves in with war by the time Tevinter showed up on the scene, and the whole display of desperate mages (lead by elven Fiona with a secret elf-blooded son in important places) indenturing themselves to Tevinter for survival (perhaps again), and it seems to me that there could be a majority of elf-blooded people walking around Thedas, especially in Tevinter. But how would anyone realize this, when we know that the offspring of elves and humans always look like humans? Perhaps these human, elf hybrids appear human in all cases, but just have a particularly strong element of elven magic in their blood – elf-bloodedness – dating back to the time of Arlathan, when there were “spires of crystal twining through the branches, palaces floating among the clouds…beings who lived forever, for whom magic was as natural as breathing." (How Solas describes Arlathan)
The point in short, I believe there are many, many more elf-blooded people in our fantasy world than is easily realized. My opinion may have been biased by reading – Masked Empire in particular and revelations of surprise half-elves in game, but I don’t think elf-blooded people are even rare. We see them, but just can’t distinguish them from full-blooded humans visually.