The Depression sometimes runs in families and may be due to heredity, learned behavior or both. Even with a genetic predisposition, it is usually a stressful or unhappy life event that triggers the onset of a depressive episode. While the exact causes of depression are unknown, several factors appear to affect its onset!
I mean it's kind of subjective topic cuz some people who get depression from a certain kind of things those things can make others happy so you can't tell like that