Have 2 things to offer: the vet said they learn it from mom cleaning them up but I was able to stop them and mom because I was around them 24-7. Maybe your pets family could not or didn't know to stop what is reported normal behavior and just let it cont.
our second litter we had: our vet also said that they could need worming meds. That worked for the older dogs and the pups were wormed during their check up. This was 4 older dogs eating poop from horses everytime our back was turned. almost immediately after they were all wormed the problem decreased 75% and we no longer have poo eating dogs.
I do think it may be a subject discussed on the internet if you google poo eating dogs and puppies but I google EVERYTHING lol. I live alone out in the boonies so google is a godsend for my inquisitive mind.
