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.
How do penis extenders work? There are two fastening points: “One at the base of the penis and one just before the glans," says Rybchin. These connect to bars or rods that "extend the length of the extender. The bars or rods are lengthened by the wearer to stretch the penis over time. Where design differences come into play is the mechanism by which the rods are lengthened and the comfort features (such as padding) of the device itself."
Not really. “My personal belief, experience and view: There is a way to make the male penis bigger, but there isn't a single universal technique that would equally add X amount of inches to every man equally. Men, in their capitalistic frenzy to super-size everything in existence while ignoring the variety of insight offered from alternate possibilities of power, identity and potency, are fiendishly focused on having the biggest *insert protruding masculine status symbol here*, and miss out on so much more,” says Malcolm Lovejoy, who is based in Toronto and is an adult film performer.
The side effects of lengthening surgeries are numerous and include infections, nerve damage, reduced sensitivity, and difficulty getting an erection. Perhaps most disturbing, scarring can leave you with a penis that's shorter than what you started with. Widening the penis is even more controversial. Side effects can be unsightly -- a lumpy, bumpy, uneven penis.