On average, women have between six and 11 percent more body fat than men, an assumed evolutionary adaptation to help during pregnancy. From puberty to menopause, women maintain more average body fat than men -- even when they take in fewer calories.
It's likely both. From own experience; in the immediate family, men are lazier. I'm on CF instead of getting actual work done.
Lazy women don't even want to go in the kitchen anymore to cook. Can't make a decent sandwich. Hard times we're living in.
Maybe it's the system but you could say high achievers in history are mostly men, but that's like .1% of all society. Despite that stat, women are definitely more harder working and are expected to keep not only themselves but the family together. Even by today's standards. Doesn't mean there aren't hardworking family men, it's just that society doesn't expect them to be. More like an icing on the cake or a "praise worthy" attribute.