There are not. There are no conclusive genes or genetic markers for depression. All that is required for someone to be depressed is to self-report as depressed and experiencing those symptoms.
"In addition, a Swedish study estimated the heritability of depression—the degree to which individual differences in occurrence are associated with genetic differences—to be around 40% for women and 30% for men...."
You seem to think that we must either know the exact cause, or we know nothing about the cause. That is simply not true.
No, I think psychology has medicalized a range of normal emotions and behaviors, like sadness and anger for example, and that there is not necessarily any such disease as depression. I know that's not PC and some may find that shocking, but it's pretty plausible when you look at the history of psychology.
Since I've already crossed the PC/shocking line... It's amazing the similarities between SSRI's and lobotomy. The mechanism of action isn't fully understood, yet some people are improved, and some people are made worse, and everyone has side effects. It was considered a breakthrough at first, then followed by controversy as people began to question the mechanism of action, the ethics of forced surgery (forced drugging) etc.
I'm not shocked. It's a sadly common opinion. I do think you're full of shit, though.
Depression is completely different from things like sadness and anger. There is a superficial outward resemblance, but that is all. They are conflated because people who have never experienced it try to slot it into what they know, so they decide that depression is just the sadness they know, but stronger. It's not.
But no, I'm sure that saying depressed people are just sad and have control over their own feelings and that Prozac is no better than a lobotomy is going to totally help people.
What's rude is going around telling people that depression is made up and comparing SSRIs to lobotomies. Getting a bit snippy when faced with such an affront is only natural.
http://en.wikipedia.org/wiki/Major_depressive_disorder#Cause...
"In addition, a Swedish study estimated the heritability of depression—the degree to which individual differences in occurrence are associated with genetic differences—to be around 40% for women and 30% for men...."
You seem to think that we must either know the exact cause, or we know nothing about the cause. That is simply not true.