 The authors tested this “three feature theory” (as they call it) using a questionnaire describing examples of birdsong that differed in Fixity, Typicality, and Function. The aim was to determine the extent to which each factor independently contributes to folk judgments about innateness. This experiment was first conducted on naïve or non-expert subjects with the aim of first determining the structure of the vernacular concept before examining its potential role in expert (scientific) judgments. As predicted, evidence of Fixity was enough for naïve subjects to agree that a trait is innate, even if the trait lacks Typicality and Function. Evidence of Typicality also independently drove innateness judgments, as did Functionality (though to a lesser degree). The authors take these results to provide a fine-grained analysis of the vernacular concept of innateness, revealing just how easily people are prompted to classify a given trait as “innate.” In a later study, Linquist et al. (2011) expanded the survey to test whether Fixity, Typicality, and Function also influence naive subjects’ judgments about whether a trait is “in the DNA.” They found that the two phrases (“innate” and “in the DNA”) draw upon the same underlying folk concept. Linquist et al. (2011) also cite examples where researchers in psychology and biology employ the folk concept in drawing unjustified inferences among i-properties. It is important to note that although these x-phi experiments are quite limited, their findings are confirmed by a much larger body of experimental work in social psychology on the ‘genetic essentialist framework’ in folk cognition (Dar-Nimrod and Heine 2006; 2011; Cheung, et al. 2014). For a side by side-comparison of the two models see Stotz and Griffiths (2018).