Investment in Sister's Children as Behavior towards Risk.

A risk-averse man will invest in his sister's children if he cares about his genetic relatedness to future generations and if he is unsure about being the father of his wife's children. The model in this paper is an advance over the earlier expected-relatedness models in that it permits mixed investment in both sister's and wife's children and also permits investment in sister's children at higher levels of paternity probability. Estimates from ordered logits suggest that paternity probability is an important determinant of investment in sister's children and that some investment in sister's children occurs even at high levels of paternity probability. Copyright 1989 by Oxford University Press.