Lindon J. Eaves (1944–2022) was a behavior geneticist and priest who has published on topics as diverse as the heritability of religion and psychopathology. His research encompasses the development of mathematical models reflecting competing theories of the causes and familial transmission of human human differences, the design of studies for the resolution, analytical methods for parameter estimation and hypothesis-testing and application to substantive questions about specific (human) traits. He was the first to consider standardized variance components for heritability estimates and was the first (at least in the human context) to consider the effects of living with a relative (with a different genotype or, in the case of monozygotic twins, the same genotype) on the behavior of a person