Most childfree people have no problem with kids at all, but just don’t want to have any themselves. There is a small section, though, that simply can’t stand to be around children, and unfortunately, they’re always the most vocal about their dislike.
This is what one couple faced because their relative hated kids and kept putting their 10-month-old son down. Her hatred became even more extreme after she moved in with them, and she said some pretty nasty things, which made her brother-in-law snap.
More info: Reddit