Measures of the degree of genetic relationship between individuals are discussed and compared from the viewpoint of the theory of kin selection. Limitations of Wright''s coefficient of relationship and Hamilton''s coefficient of relatedness are discussed. Jacquard''s theoretical framework of predicting genic structures is employed in hopes of clarifying issues such as measuring genetic relationships between inbred individuals, the effect of population gene frequency and measuring asymmetrical genetic relationships. [This study has applicability to animals and humans.].