It may be a mistake to consider genes as only a "millions of years" timescale. After all, the human species hasn't been around a fraction of that, and there is a lot of behavior that is genetic which we otherwise wouldn't consider to be so. Pinker's "The Blank Slate" has a useful discussion on such. If half of personality is genetic and half random (and the genetic part is itself a somewhat random combination of two other people's genes and randomness), then genes are possibly the largest tentpole.
It may be a mistake to consider genes as only a "millions of years" timescale. After all, the human species hasn't been around a fraction of that, and there is a lot of behavior that is genetic which we otherwise wouldn't consider to be so. Pinker's "The Blank Slate" has a useful discussion on such. If half of personality is genetic and half random (and the genetic part is itself a somewhat random combination of two other people's genes and randomness), then genes are possibly the largest tentpole.