Statistics
R v. 3.3.1 (R Core Team, 2018) was used for all statistical tests. Associations of Rh genotype with sex were measured using a contingency table and the association of these two factors with physical health problems score and mental health problems score (which had normal distributions) was tested using ANCOVA (Type III sum of squares) with the age of subjects as covariate. Associations of Rh genotype with source health-related variables (which had mostly highly asymmetric distributions) were measured by a (nonparametric) partial Kendall correlation test (R package ppcor 1.1 (Kim, 2015)) with age as a covariate. Correction for multiple tests was done using the Benjamini–Hochberg procedure with a false discovery rate pre-set to 0.20 (Benjamini & Hochberg, 1995) using the Excel sheet published by McDonald (2014).