They probably are to some degree, or at least I wouldn't be surprised if they were. I mean if there are going to be genetic links for intelligence and depression why stop there?
Because I see the brain as a collection of neurones that doesnt determine how we think, they just provide the mechnism to do so. How we think is dependent on our prior experiences, and our logical & creative intelligence in how we interpret them. Depression is down to chemical factors such as how much seratonin is pumped into the brain.
Do you believe being hard working/lazy, being confident/lacking confidence, capitalist/socialist, spritual/non spiritual are factors controlled by genes?
I see these as being different as they are behavioural. We have all experienced both extremes during our lives, so it cannot be a congenital condition and thus dependent on our environment at the time.