Twin studies (separated at a young age/at birth), dog breeding, and fox breeding studies have shown that things such as docility/aggressiveness have genetics as a major contributor (actually the primary contributor, but reasonably discussing such a controversial topic doesn’t seem fit for a comment section of a webcomic).
While a “conflict gene” is perhaps a gross oversimplification, certain genes deal with certain behavior. On a cellular level, this can deal with how reaction cascades from certain environmental stimuli proceed. Genes can influence things such as spatial organization and cross-talk of certain enzymes. Such cellular organization can influence intercellular communication, such as between neurons. If the cellular level seems unconvincing due to it being an individual cell or a colony of identical (or near identical) cells, then there is the genetic influence upon how an organism develops, particularly it’s brain. Genetic influences upon such things as autism, basically genes affecting the wiring of the brain, can cause differences in behavior, no? There is also the genetics behind the development of the brain between different taxa, does this not influence behavior?

I agree that certain people use arguments of “nature” to protect their “status quo,” but they often seem to have certain gaps in their understanding or work upon unsupported presuppositions. Humanity should continue to move past certain “wild” limitations. But simply ignoring (or bashing) the evidence for something doesn’t mean it’s just going to go away, and how it works will fall within your lines of thinking. Also, “stupidity”? While there are people who do argue without much backing, dismissing an entire line of thought (without much backing) is not conducive to reasonable discourse.

From what you say about how you “read stuff,” along with what you say from it, I’ll guess that it’s more of people talking about “science,” rather than people talking about scientific principles or the accounts of the evidence for principles themselves.

@ Gabi (or anyone who wants to read this, I suppose): While things worded well can be quite helpful, please keep in mind that we should first look to what is said, not how it is said.
If you would like to read further on the subject of genetic influence upon behavior, I would suggest reading up on the breeding of foxes in the Soviet Union. “Fun” thing about it is that they were actually doing it while giving false pretexts to the Soviet Union, stating that it was just raising them for fur. This was due to Lysenkoism holding sway in the political climate, causing some to even die for studying Mendelian genetics (like Nikolai Vavilov). But now we have learned a great deal about genetics, behavior, and genetic linkages (regarding traits that are linked by virtue of spatial relation if not direct influence). An added bonus is that the docile breeds of foxes can be purchased as Pets!