I think there is a genetic component, but it's only a component (part of the story, not the whole story).
My brother and I are adopted (and not related) and our weight patterns are very different than each others and very different than our parents and siblings. Of our two sisters (my parents' biological children) one follows the weight pattern of our mother and one follows the weight pattern of our father.
I'm the only person in the family (immediate or extended) to have been overweight as a child or before their mid to late 20's. I was severely overweight in kindergarten, and morbidly obese by puberty (225 lbs at 12 years old).
Even of the family members who were obese as older adults, no one in the family ever came within 120 lbs of my highest weight.
It does make me wonder what the weight/eating patterns of my bio-parents were.
Of those of us with sugar/carb issues, I don't think it matters why or how we got them. We're stuck with it, and have to work around it.
I'm just really glad I discovered the carb connection, because limiting and restricting carbs makes weight loss and my life so much easier. We're a carb-flooded culture, so it's not always easy to maintain the carb level that's best for me, but knowledge is power. I now know a way to keep my hunger in check and lose weight without feeling half-starved and deprived.



(with a nod to Joey from Friends) 
