I saw this video and realised that all mentioned Old English plurals sound pretty natural for me, even though I'm native Czech speaker. Also in German I think inflection seems to follow some universal model. For instance, female form you create by adding -in. But for example word Hündin ( [hʏndin] - female dog) is an exception which I think relates to the meaning much more than [hundin] would.
What is this caused by? Is the more open vowel in plural/female form common also for Asian or tribal languages or is it ingrained just in the Indo-European ones? Or am I just influenced by the life in Western culture (or used to the correct forms)?