This is the sort of leap from science to sensationalism that leads many people to believe they are helpless to control their own state of mental or physical health. These headlines strip away power from people, making them believe that they have no control over their own state of happiness. In reality, people have near total control over their brain chemistry -- and even serotonin levels -- by making daily choices about foods, physical exercise, use of stimulants drugs like caffeine and so on. In fact, one of the most powerful ways to boost serotonin in the brain is to expose your skin to natural sunlight, and it works no matter what your genetic makeup.
Too often, lazy journalists write sensational headlines about research into the genetic influences on human healh without considering the fact that such headlines actually cause many readers to believe their own state of health is predetermined. If genes are responsible for a person's health outcome, then why should they even try to make any changes in their own health? These headlines cause many people to stop making healthy choices and return to abusing their bodies with junk food, lack of physical exercise, and processed foods loaded with hydrogenated oils or added sugars. But as is always the case when it comes to chronic disease and mental disorders, genes are merely small influencers on the actual outcome, and nearly any genetic predisposition can be overcome through changes in nutrition and physical exercise.
The only exception to all this is the all-powerful gene that turns newspaper journalists into babbling science idiots. I'm not sure that gene can be overcome at all.