The short answer to that is, yes, the genetics that you are born with can have an impact on your body
In the past ten years, the studies on just how much genetics impacts body weight has become much more sophisticated- as it has all come out, it has shown that this is not as simple as it was once considered and this is a complex, multi faceted issue. There are actually only a couple of exceptions where one genetic mutation results in the more severe cases of what is known as morbid obesity. At the same time, though, there are a multitude (In the hundreds) of genes that effect one's susceptibility towards overeating, and as other genes come into the mix, this enhances that vulnerability.
These are not the only factors, though. Most current research shows that the environmental conditions of the fetus during pregnancy will greatly impact
In short, what all of these studies are indicating is, is that if you feel that your weight gain is predominately due to genetics, you may not be entirely wrong. However, it is generally in the patterns where you find the influence of genetics on your own body weight. All of these developments are actually a very hopeful look into what may be able to happen for those who have had long term weight related issues, because, this shows that the behaviors, though yes, genetically predisposed, are correctable. For many, this comes as a wonderful sort of revelation because it does mean that they are not held at the mercy of issues that are completely beyond their control.