» Wed Nov 07, 2012 10:07 pm
http://www.imperial-library.info/content/notes-racial-phylogeny-and-biology
In a nutshell: children are always the race of the mother. They can inherit some minor traits from their father, but they'll look like whatever race their mother is.
Bretons are in fact a hybrid race - Pocket Guide to the Empire calls them "Manmer". They're a result of centuries of mixed marriages between the Aldmer and the Nedic people. Similarly, Bosmeri elven blood might be a little watered down too, as they're believed to have taken mannish wives in their early years. However, this only occurs after generations of interbreeding, so you won't see it immediately.
As for Argonians, IIRC we don't even know if they're fertile with humans or elves. There's no proof of this in the lore.