How specific? Steroids can make people more aggressive and presumably more attracted to aggressive ideas. Adrenaline can do that in the short term. There are ma

How specific? Steroids can make people more aggressive and presumably more attracted to aggressive ideas. Adrenaline can do that in the short term. There are many such mood altering substances that DNA can code for. We know that they can be set to trigger by the environment, as in mood changes in the presence of a potential mate or predator. It may be that as behavior driven by memes versus genes diverge enough, the population naturally falls. That could be the solution to the Fermi paradox, that sentient population growth is limited by the growth of their meme pools, as they diverge in purpose from their gene pools.