Is it normal to hate other people's kids?
Depends.It depends
It’s normal not to enjoy being around other people’s kids, especially when they’re loud or badly behaved. Feeling annoyed is different from wishing them harm or treating them cruelly.
You don’t have to be a kid person. Some people find children noisy, sticky, or exhausting, and get especially irritated when their parents expect everyone else to accommodate them. That doesn’t make you a bad person; it may just mean you prefer adult company or need more space.
“Hate” can mean anything from “I don’t want to babysit” to genuine hostility, though. The first is a perfectly ordinary preference; the important part is keeping your boundaries respectful and not taking your frustration out on a child, who’s still learning how to behave.