Genetics, some people use them as an excuse for looking bad. "I have bad genetics, therefore i must be fat and get picked on and made fun of and be called fat" or "i have bad genetics, therefore i will always weigh 100lbs and get beat up by everyone because im so skinny." That is all total 100% bullshit! If your fat, its not your genetics, sure they play a part in making you fat, but its your fault you stay fat! If your skinny, stop complaining that because your dads so skinny, and your mom is so skinny, that you will forever have to be a skinny little punk. Its your parents fault for giving you those skinny genes, but its your fault for staying skinny! The skinny kid can gain weight and put on muscle, and the fat kid can loss weight and put on muscle. Everyone can win, you just have to play the game and play it right!
There are 3 body types...
Ectomorph - These are the skinny people. These guys have the fastest metabolism of them all. The ones who have been skinny all there life. They are skinny for a reason. This body type makes these ectomorphs lucky and unlucky. Good news, they are lucky because they will always have a lower body fat then all the other body types. These guys will be able to loss weight and loss fat faster then everyone else. Bad news, its extremely hard for these guys to gain weight and muscle mass. These guys have to eat and eat and eat to put on just a little weight.
Mesomorph - These guys have the best of both worlds. These are the in-between people. The ones that might be skinny, might be fat, or might be in the middle. They have a metabolism slower then the ectomorphs, but its a little harder for them to lose weight, and a little easier for them to gain weight..
Endomorph - The slowest metabolism of them all. These guys have the hardest time losing weight and keeping it off. But these guys have it easy when it comes to gaining weight, problem is, they gain to much..
Figure out which one is you. I am an ectomorph, I was always refered to as "skin and bones" by my grandma. But just because im an ectomorph, that doesn't mean i can't be 200lbs of pure muscle, with a 5% body fat. And the endomorphs can be 120lbs if they want to be. They can be called skin and bones by their grandma's. They can also be 200lbs of pure muscle, or.. they can even be 275lbs of pure muscle because of their weight gaining ease. Mesomorphs can be all of the above..