Is there a biological basis or genetic predisposition for depression?

Research suggests there is a genetic predisposition to depression. I think that people often misunderstand when we say there is a genetic reason for depression- it’s not a genetic cause. It’s a genetic predisposition or genetic risk for depression which could put the person in a particularly vulnerable position to develop depression, but this risk is not unavoidable. If you’re at genetic risk for depression, it does not mean you will develop depression. So this also depends on outside factors, and there are probably multiple genes, like thousands of genes, that could contribute to the increased risk of depression and each of these genetic variants will contribute only a small proportion to the risk. So you might have many genetic risk markers in combination that will increase your predisposition to depression in small proportions, but then it also heavily depends on your environment.