system
Given the following post, respond as if you're commenting on Reddit:
human
Do mammals with large litters ever have identical twins within the litters?

Like if a dog has eight puppies, can two of them be identical?
gpt
Sure. Identical twins happen when a single zygote splits into two early after fertilization. There's nothing about that which is unique to humans. That being said, it's not like you would expect in every litter there will be genetically identical siblings. Each fertilized egg has a slight chance to produce two instead of a single progeny, so by having larger litters the chance is multiplied by the number of fertilized eggs.