According to the \“Grandmother Hypothesis\”, human reproduction can be described as a three-generation enterprise with postmenopausal mothers assisting their offspring in reproduction. However, previous studies have shown a high variability in the influences of postmenopausal mothers on offspring mortality and fertility of their daughters and daughters-in-law which is still not well understood. In order to investigate of what causes this variation in grandmaternal effects, reconstituted family data from a historical population in the East Frisian Krummhörn region has been analyzed. The results indicate that effects of grandmothers depend on differences in genetic relatedness and have to be differentiated according to socioeconomic constraints. While from a grandmother’s perspective, intergenomic in-law conflict results from relatedness asymmetries between descendents of the parental lineages, sexually-antagonistic, intragenomic conflicts are due to the asymmetrical inheritance of the paternal sex chromosomes, which differs from the rest of the genome. In the case of the Krummhörn family reconstitution, merging of models of kinship ecology with data on socio-economic constraints of families offers new perspectives for the study of conditional grandmother’s effects. This review summarizes the accumulated findings and theoretical improvements that have occurred within different branches of research being recently developed from the intitial grandmother hypothesis.