Do you see how absolutely flawed your argument is?
No, but I see how absolutely flawed yours is. It's called the straw man fallacy. Here's what you said:
To believe that genes are the only cause of depression is absolutely idiotic on so many levels that I don't know where to begin.
Emphasis mine in the quote above. Your argument is, of course, absolutely correct. Unfortunately it's not what I've claimed and it's not what this study claims. You're arguing against a position that doesn't exist. This is what I've said:
It's been known for quite some time that both depression and predisposition to suicides have a genetic component.
A component, as in one factor out of many. In addition, I also said:
you most certainly should be able to test someone's blood to determine if they are at an increased risk for depression
I didn't say you could test to see if someone has depression, I said you could test to see if they have an increased risk of getting depression. So now that we've cleared that up, I can address your other comments.
If you don't get it, rate yourself for desire to commit suicide today. Go tell our boss to "f&%k off" and quit your job, and apply only for rocket science positions at NASA. After your unemployment runs out, debt is through the roof, you sell everything you own, and you live on the streets with no family of friends measure your desire to commit suicide again. I'll bet that you feel much more inclined after losing everything you have of value and having small hopes for a future.
First of all, I'm pretty sure I would still not commit suicide. I would quit doing idiotic things and get my life back on track. And it would be fairly easy to do so under your scenario. That's not to say there's nothing that would make me consider suicide. If I found out today I had early-onset Alzheimer's, I would consider suicide before it gets to the point where I'm no longer capable of taking care of myself. If I found out I had terminal cancer and a sufficiently low probability of recovery through chemo, I might consider not suffering through chemo, and instead spending the rest of my relatively healthy life with family and friends, and committing suicide when the cancer effects get sufficiently bad. That's not to say I have a genetic predisposition to suicide, I probably don't.
That said, you know those stories of kids who get bullied on facebook and decide to commit suicide? Or those people who commit suicide after their boyfriend or girlfriend breaks up with them? The vast majority of people would never commit suicide under those circumstances. But if you have a genetic predisposition, it might be enough to send you over the edge. Detecting this and being aware you're at an increased risk could lead you to take steps to prevent it by forming a support network, going on medication, avoiding medication known to increase suicide rates, etc.
As a real example, I've paid for a genetic profile on myself and know that I am at increased risk for Type II diabetes. That doesn't mean I *have* Type II diabetes. It means I'm more careful about what I eat now, and watch my weight carefully. I also know I'm at increased risk for certain types of cancer, so I started getting screened for those at an earlier age to increase my chances of catching it early if I develop it. Which I might not.