Hey,

I think that is a mix of both...as for genetics, I don't know who had depression in my family because for them it was a taboo subject...but in terms of neurobiology and all that, I believe that patterns or habits of thought can affect the biological functions of the brain and change its chemistry or wiring. So thought can change biology overtime...like if we don't think positively, that pathway in our brain weakens and it makes us harder to access that positivity...I dunno if that is true, but it makes sense to me. And biology can affect thought, like I certainly believe that I have low levels of serotonin...as long as I can remember I've never been the super bubbly type. So biologically I would be more susceptible to having a low mood? If only it was so easy to figure out, I would probably be feeling like a million bucks if it was.