I do not and never will accept genetics as an excuse for bad behaviour and choices. People like to jump on genetics as the latest excuse in a long list of excuses for being unable to do something. I think the way we are raised has a much more profound impact on these things, and that is something that should be looked at closely. Regarding the self esteem issues of many people, I feel that is indeed an area for concern and they do definitely need help to overcome the issues holding them back in their lives. But they need true help, something that will break through the issues and actually deal with them so they can move on. Too often the "help" merely masks over the cause by treating the symptoms, hence the drug co's stranglehold on the health industry. This kind of treatment is pointless as the underlying issue(s) are still there and continue to come up throughout their entire lives. We really have to change how we as a society treat psychological issues.
With you on this one buddy. People use age, genetics, whatever they can as a defense mechanism to exempt themselves from personal responsiblity. "Oh, I can't lose weight, I've got an endomorph build, it's just in my genetics" Well people 100 years ago weren't obese, genetics haven't changed much in 2 or 3 generations. "I can't exercise, I'm too old". My personal favourite: "I've got an addictive personality." Hahaha. Sorry, but that's a scientific way of saying "I have no willpower".
As a free man (or woman) you ought to take responsiblity for your actions. This all said, we live in the type of society that makes it perfectly okay to be average, and even provides us the excuses.