Board Thread:Lore Discussion/@comment-25291590-20130317093523/@comment-17114085-20140409195741

Not to mention the Argonians are reptiles that lay eggs. Which means it is biologically impossible for them to interbreed with Mammals. Though in TESU there is magic, meaning you can probably make an abomination of nature like a reptile-mammal hybrid using some kind of magic. Though this has never been done before for all we know.

It has been alluded in the Real Barenziah that Khajiits and Dunmer can interbreed, meaning they have to at least be able to interbreed with other Mer. If they can with Men is uncertain.