To detect underlying biological pathways of importance to personality, all genes with an empirical p value below p = 0.01 were included in a pathway analysis using the Ingenuity Pathway analysis program (Ingenuity Systems, release IPA 6.0). The Ingenuity database contains large amounts of up-to-date information (based on scientific publications) about the localisation, structure and biological function of proteins and their interactions. By means of pathway analysis it is possible to check whether the genes most associated with personality in our gene-based test are more prevalent in any known biological or canonical pathway than would be expected by chance. We set the alpha level at 0.01 and p-values for each pathway were corrected by the Benjamini-Hochberg multiple testing correction as implemented in Ingenuity. We used an alpha level of 0.01 rather than 0.05 to account for the multiple traits testing.
