Yes genetics are a big deal, and sometimes you cannot avoid when it's your time.
Anyone who believes they can just let themselves go and be unhealthy and not pay a price is kidding themselves though. Sure you could be THAT guy who lives to 100, a la smoking freak George Burns, but, the odds are against you.
I recall watching a documentary and it was about bad health, poor eating etc and they interviewed Americans in fast food places who were clearly overweight, as they ate massive meals and a massive drink. The one point I took from that show was the candidness of these people, they admitted they eat like garbage and they expect to die early. As one guy put it, I paraphrase, "I love food too much, so I accept my fate" It stuck with me, because in contrast Canadians take offense to the obvious. I know guys who are 100 pounds overweight who believe they are in good shape. We are extremely sensitive to facts and reality if it's inconvenient to our own self image.
As long we understand. I have family who are overweight, I worry about them. Technically, by strict standards I'm overweight, but I have fairly low fat content. I put on weight from years of heavy lifting and sports. My once skinny, zero fat structure became more muscular as I lifted heavy and ate alot of protein for more than half of my life (it was my own personal challenge since I didn't play sports anymore but wanted to stay active).
I know I carry risks for having more weight, even muscle mass, which is why I'm happy to sacrifice muscle mass now, for a more lean body.
I hope we all take note of these stories and try to stay healthy. It's not easy, and as we age it doesn't get any easier. I always read up on people onhere talking about health issues and such. One of my favourite subjects to be honest.
Stay healthy folks. We need a few people who have working brains to help this world out

It's not just weight of course, it's our internal organs, our lungs, our brains and especially our arteries. Take precautions, especially if you love a less than optimum lifestyle.