Actually, genetics do play a role in one's body's size and more importantly, body shape (articles here and here - my browser would not let me link the actual journals). Not everyone can have washboard abs or a body like X celebrity. While yes, we should never blame genetics for our lifestyle, what is healthy and fit for one individual may not be healthy and fit for another.
Looks like someone found an article to justify their poor eating habits. Keep making excuses for yourself. I'm not buying it.