Evolutionary Perspectives on the Loss of a Twin

Abstract

The nature and origin of kin relations, and their implications with respect to familial inheritance, parental favoritism, resource provision, and other social and caretaking behaviors, have been of considerable interest to evolutionary psychologists. Comparative analysis of the grief intensity ratings of bereaved monozygotic (MZ or identical) and dizygotic (DZ or fraternal) twins, guided by kinship genetic theory, offers a novel approach to understanding the effects of genetic and social relatedness on bereavement. This chapter focuses on twin analyses, using kinship genetic theory as a backdrop for generating and testing hypotheses related to differential bereavement reactions between relatives. At the distal (functional) level, a deceased cotwin represents a loss of reproductive potential for the survivor. This is especially true in the case of MZ twins who are genetically identical, as indicated earlier in reference to the twin-family study of social closeness. The concept of paternity uncertainty is also relevant in the context of bereavement. Paternity uncertainty refers to the fact that a male can never be certain that he is genetically related to a child delivered by his partner. That is because of hidden ovulation, internal fertilization, and continuous female sexual receptivity. (PsycInfo Database Record (c) 2021 APA, all rights reserved)