Definitely yes, if you have a big or small penis is mostly defined by your genes. Sons of men with a large penis often have a large penis. Sons of men with a small penis often have a smaller penis. There are certainly exceptions, but in general genes are very dominant when it comes to erect penis size. From my own experience and research, genetics are the most dominant factor in size, environmental factors or lifestyle only have very limited to no effects.
The vacuum pump. This is a cylinder that sucks out air. You stick your penis in and the resulting vacuum draws extra blood into it, making it erect and a little bigger. You then clamp off the penis with a tight ring -- like a tourniquet -- to keep the blood from leaking back into your body. What are the drawbacks? The effect only lasts as long as you have the ring on. Using it for more than 20 to 30 minutes can cause tissue damage. This is sometimes used as a treatment for erectile dysfunction, but has not been proven to actually increase the size of the penis.