Birds have a quality known as broodiness. It means that, after they lay their eggs, they stick around and take care of those eggs. Most commercial chickens don’t have that quality. And it looks like their complete disregard for their offspring results from one genetic mutation.
Having raised chickens, both for meat and eggs, I never thought about this. I’ve certainly seen broodiness in other fowl, like geese and ducks. You only have to get bitten by a goose once… Not me, I just watched 😀