Hi,
some years gone by since that thread started, but I also have the problem with the brown eyes. And I don't have it since the beginning, I have it since, I guess, some weeks.
Maybe it started when I installed Cottage living, that parents small addon (don't know the english name) and that toddler pack, or it started earlier and I just didn't recognize it till yet.
But I play Sims4 since maybe 2-3 years now, so I can say for sure, it is not from the beginning.
Also if there are much more people with dark eyes, but this is really TO much, almost all my Townies and unplayed Sims look like that and when I roll the dice in CAS there's also so much brown and black. Often more than 10 -15 times brown/black before there is one time coming another colour. That's not variety in my eyes.
Removing all Mods and Downloads and deleting cache files and repairing the game didn't bring any changes.
I'm really not happy with this.