I think depression can be one or the other, but if it is it'll only be to a slight degree (if it runs in your family you might be more prone to moodswings, seeing things bleakly, etc and if you've been through horrible things that can make life seem pretty crappy too). But if you get it bad then you are probably being hit by an onslaught from all angles.
Mental illness runs in my family (on both my mum and dad's sides so I didn't have much of a chance). Plus I went through a lot of less than desirable experiences (one of the psychiatrists I have seen over the years has labelled me with Post Traumatic Stress Disorder because of the effect that what I have been through has had on me). I also think it has another factor. One that isn't just about inheritance but is still about genetics - the way that you were born. Our personality type. This dictates the way we react to a situation (if you can't admit that you are wrong, for example, you get worked up trying to prove you were right when you clearly weren't). One way of putting it (and it isn't the most healthy I'll admit) is the amount of flaws I have - my mum once said she thought I inherited all the flaws in the family - all of that in one person doesn't make for a very good outcome!
Basically I was born different, I was always bound to have a tough time, but had people treated me better I'm pretty goddamn sure I wouldn't have ended up this screwed up - unable to function, haven't worked for years, always ill with phsyical symptoms, head a fuzz, constant panic attacks, etc etc. So my answer is that depression is a combination of both genetics and environment.
Life circumstances from childhood on caused my issues to develope but there could be physical tendencies to develope problems also. Only God has this answer for sure.
Circumstances yes, gene tendency yes!
Signaling process in cells (even brain cells) involve a dozen or more proteins, each encoded by a separate gene. If a mental illness is due to a breakdown in this signaling process, then a defect in any of those genes could be the cause. Hence, no single gene may account for a mental illness like depression, bipolar disorder, or schizophrenia. There are a myriad of genetic defects that may lead to a mental illness, sometimes (but not always) with the right circumstances (life factors). The fact that multiple genes may be involved in mental illness is not unprecedented: cancer is another disease where multiple genes are involved. Sometimes a gene may be more likely to cause cancer (like BRCA1 and BRCA2), but the signaling processes that go awry leading to malignancy are governed by dozens of proteins. If any one fails to do its job, cancer will develop.
I don't usually respond to these questions on the internet, but this one I had to. I do not need to see a study or have a series of physicians tell me something I have known almost my entire life. I suffer from Generalized Anxiety Disorder and Major Depressive Disorder. My great-grandmother suffered from what was then called "melancholy". Both my maternal grandmother and grandfather suffered from depression and anxiety. My own mother and aunt suffered from depression and anxiety, particularly my mother who in addition had severe panic attacks. My maternal grandfather had what was called a "nervous breakdown" and my grandmother had to go to work to support the family. My sister has panic attacks and depression, although not as bad as mine. I've been sufferering, as I previously stated, since I was about 16 and I'm now 49. Moreover, my son, daughter, niece and nephew all have anxiety disorders and bouts of depression. Pretty much not one member of my family on my mother's line has been spared the from real, serious and life changing depression and anxiety; there is no way this is a coincidence, there is no way it can be.
I think that there is definitely a predisposition in certain families for their members to become depressed and I therefore do believe that there is probably some genetic influence at play. I also think though that strategies we use for coping are learned behaviors ( children will use the same or similar coping techniques as their parents...overeating, drinking, "seeing the glass half-empty or half-full", looking for solutions,etc). So if the adults in my family were problem solvers who attacked a difficult situation with optimism and energy, I would probably learn to view difficult situations as simply something that needs to be overcome. If however, the adults in my family have negative ways of coping such as drinking, depression, etc. then I may develop negative coping skills, be likely to experience frustration or even hopelessness when confronted with obstacles. What I think is tricky, though, is that we are born with certain temperaments (fussy, calm, etc) and these temperaments form a synergy with our environment in determinig how we respond to situations. So I guess that what I'm saying is that I really don't know the definitive answer, but I have the strong opinion that both nature and nurture operate in defining whether or not a person becomes depressed.
The more Reports/studies that I read, the more confused I'm getting. I do believe that sensitive souls,those who received scripts like 'youre worthless' as children have a higher chance of developing Depression.Anxiety-Suicide-Depression is supposed to be in our DNA according to other studies. Im just wondering though, why in 2009, we have an 'epidemic' of Depression, surely this cant be just DNA ? Cant be just bad parenting. Alot of people come out of awful orphanages and go into good marriages and go on to be good mothers and fathers and quite happy - I do think that the break down of the traditional family with its support systems and the breakdown of Community has alot to do with the Isolation of Depression, particularly, amongst the elderly. The Medias/Advertisings brainwashing re: the Peter Pan syndrome, the perfect body syndrome. Weve never been better looking for our age and never been more miserable. In short, its half a dozen of one, and six of the other.