molly coloration tied to aggression?

[Phoenixphire55]

So I've heard that dalmation mollies tend to be more aggressive than other mollies. I have three sphenops mollies and two yellow mollies. The yellow mollies are very peaceful and not aggressive at all. The sphenops mollies are definitely more aggressive. Weirdly enough, I've noticed that the darkest sphenops molly (fittingly named Medusa) is noticeably more aggressive than her sisters (Euryale and Stheno... I like Greek mythology) who have significantly more white scales than Medusa who has very few. This may be a boring topic but I'm just curious if anyone knows why coloration is tied to aggression, cuz it seems weird to me since they weren't bred with these colors in the wild via evolution.