Chapter 5 continues describing the theorized causal progression from molecular and behavioral genetics, to neuroanatomy and neurophysiology, through to behavioral development under varying degrees of environmental adversity, coming now to this chapter, which wades into the depths of personality and related individual differences as they have been used to predict political ideology within the social sciences. Herein, the authoritarian personality, social dominance orientation, dark triad traits, moral emotions, and visions are reviewed alongside individual personality traits such as openness to experience and conscientiousness. Many of these theories are valid and compelling. They collectively establish political ideology as a biologically based, heritable worldview; an “applied political philosophy” (Heywood, Political ideologies: An introduction. Bloomsbury Academic, 2021, p. 9) that covaries with personality. Still, with the exception of Haidt, none of these frameworks explain why personality and ideology covary, and why either are aspects of human psychology. Though this chapter primarily reviews existing literature, it ends by discussing these individual differences as strategic variation evolved via a process of negative frequency-dependent balancing selection. With this foundation, readers can then see, in Chap. 8 , how this evolved variation is couched in the broader framework of multilevel selection theory.