Psychology
Two rare things co-occurring tricks your brain into seeing a pattern
When two things are both statistically uncommon, seeing them paired even a few times makes the pairing stand out in memory, so you overestimate how often they actually go together. Hamilton and Gifford showed this with fictional groups: a minority group paired with rare bad behavior got remembered as 'more prone' to it, even though the real ratio of good-to-bad behavior was identical across groups. It's one mechanism behind stereotypes forming with no real correlation underneath.