It was a 2011 study that found a 0.28 correlation in amygdalae size vs conservative political identity among a tiny group of college students. A replication attempt dropped that correlation to 0.068 which is basically nothing, and completely failed to replicate at all the other, even weaker, findings of the previous study. And the media called the amygdala the "fear center", which is dumb. It plays a key role in memory - especially long term memory, emotional processing, the understanding of social cues, and more. Removing it would render someone extremely mentally retarded.

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I'd also add on this issue that considering political issues among college students is itself silly. Our political positions on things is impacted by our life experience, and at the point of college one has very little life experience to formulate views off of. Political identity will often shift radically from age 20 to 40, which against suggests a genetic basis as being farcical - at least beyond the point that your brain structure will typically correlate, to some degree, with the development of skills, identity, etc.