Can be  the depression  of origin  genetic?

Nowadays, stress in our society can contribute to the instability of the lifestyle of the person and cause depression. According to the comprehensive health Yukioske magazine, Dr. Flora lopez defines that depression as a disease that affects the mood of the sufferer as well as the integral functioning of the body. Dr. Flores Lopez says It  is not the same feeling sad to be depressed, because sadness is a natural emotion and short-term depression is  in a long-term, with features such as, lack of appetite, a lot of sleep, feel tired, weight loss and think  in  death. She believes that depression is caused by three factors that are; genetic because It is inherit, brain because, there is an imbalance  neuronal and social because, the person can not keep a  stable relationships and  can have a greater risk of depression. Therefore, According to Dr Florez the person with depression should receive psychiatric treatment and medication.  But from my point of view I agree with the doctor in some things as the definition and difference between depression and sadness, but I disagree on the genetic factor of depression because I think that depression is a mood abnormal that comes with the passing of the years, and when you saved a lot of feelings for a long time and you do not know expel and with the passing of the days, months and years this feeling often leads people to death.