[Carrie]

I don't agree that it's genetic.
I do however think that much of it is physical - there are problems with thyroids, patuitary glands, etc that affect weight and these things *cannot* be helped.

Most of it though (IMO) is laziness and lack of willpower. Willpower as in going through the grocery store without buying ice cream and frozen pizzas, willpower to pick up an orange or an apple instead of pulling a piece of cheesecake out of the fridge.
Laziness of course to not exercise, but also being too lazy to cook a meal and instead hitting the McD's drive-thru, slapping a frozen meal into the microwave, or just eating an entire bag of snack doodles rather than getting up and cooking yourself something to eat.

I think it all starts in the brain. If you can train yourself that certain foods aren't "treats" or "soothers", and know that there's really no reason to be eating something because it's so ungodly unhealthy for you, and keep from even bringing these things into your house, then you'll have a much easier time with your weight.