system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do some cats look completely different from both parents and siblings?
gpt
Female cats often mate with more than one tomcat - and it's common in this situation to have kittens in the same litter which have different fathers.

The mother is the same (obviously) but they can and do look very different from their siblings and from what you might have thought the father was.