Mother, father, brother, sister, daughter,… son?
Can I rightly assume that something resembling “-ter” was an indo-european suffix designating a blood relationship?
If so, what the heck happened to the word “son”? It doesn’t appear to have ever had the suffix (at least, not since PIE times), while each of the other words has always had it. I doubt that it’s a pre-PIE loan since familial terms tend to resist change… and the PIE speakers were patrilineal, so the word for “son” would have been of extra-special importance. Hmmm… could that be the very reason for the lack of a suffix? Maybe *sunu originally meant something like “heir”, and only during PIE times did it begin to specifically refer to one’s male child?
If “-ter” is not a suffix, then why the similarity across so many related words?
Anyway, I’m just wondering.