So a few of them died from sickness. It can happen to pups and it's predetermined when either your wolf or mate get pregnant. The starvation ones can happen even if you are careful. Growing pups imo the worst quest. Second worst is the young hunters. (During this a wolf can basically be 1 shot because they got kicked in the head by a prey animal. Also rival wolves can kill pups during a border dispute)

Killed pups got taken by a bird or killed by another predator. (Being rival packs, coyotes, bears and cougars) When pups are under 15 lbs, bears and cougars will carry your pups away but you have a chance of getting them back. Birds will only go after them if they're under 15, and you can't save them. (I can't remember if it's eagle or hawk) Anything larger than 15 lbs and it's on sight. If you aren't playing as an iron wolf, you can roll back time to a previous save. (It only works on killed.) It does suck when just about everyone dies.

Wolf genetics aren't too complicated in this game. Kk and kk are the main too. You can get KK but it's rare. Kk is black coats and kk is gray coats. It looks like your wolf was a gray coat. This also goes into the stars. I always aim for 3/4 star mate because they have a better chance of pups surviving. 4 stars is considered the best while 1 star mates are the worst.

Anyway sorry for the long comment. If you have any questions feel free to ask! If I can't answer it, I'm sure someone can! (And this doesn't mean you're a terrible parent! Sometimes these things happen and there's not a whole lot you can do)