Why I don't believe the genetics excuse anymore A little background, My father, brother and sister are all fat, my mother and I are not(I'm a dude). Growing up, I always believed that the size difference was genetic to some extent. Portion sizes were always similar in our house, even for my father, and a second helping was not uncommon. What I failed to realize at the time was the different lifestyles we led. For example, my siblings didn't play any sports that require breaking a sweat, and my dad was/is a business man who led a relatively inactive life. My mother isn't a big lady, and she doesn't eat much, I played sports. After growing up and living away for a few years, I moved back and discovered a few things that changed my mind. First was that after getting married, my brother ballooned to double the size he was when I moved away and I am personally unaware of any genetic disorders that can cause 150lbs of weight gain during your mid 20s.  The second was that after moving back, I went and had lunch with my dad one day. We met at a fast food restaurant near his house and, to my surprise, the girl working the register quite clearly recognized my dad. Not in the "I've seen you somewhere before" way, but in the "Here's one of my regulars" way.  This is when it all sort of made sense to me, it's not portion size that is their problem, but the frequency with which they consume those portions as well as the type of food being consumed.  So I no longer believe people are predisposed to being fat. It took me until my 30s but my eyes are now wide open and my sympathy well has run dry. That's it, been a lurker here for awhile, figured it was about time to share something.