Personally I would say there are various factors in the "determination" of the physical traits of a person. For example, if you go to the gym or do any physical activiy, it develops your muscles so obviously it affects your physical trait. Also if you have a good hygiene (take care of yourself), if you eat healthy are all factors that contributes in the determination of the physical trait. It also depends in the environement that you live in, For example if you live in a household where violence, stress and so on are present, chance are that It could affect your physical traits especially the facial part of it. Work is also a factor (If you compare someone who works in construction with a lawyer, the posibilities are that the guy in the construction is more rough and more "man"). The genes are also very important, if both your parents are "fat" chances are that you will also be. I believe there are more factors but I would personally says these ones are the common ones. Hope it helped you !