Human kin investment as a function of genetic relatedness and lineage

From the book : Evolutionary Psychology 2: 129-141.
Two independent samples of students were asked to allocate fictional lotteries of varying dollar amounts to their blood relatives.
In both studies, a reliable genetic relatedness by lineage interaction emerged, such that the genetic effect was a more positive predictor of percent of money allocated for relatives of a direct lineage (e.g., parents, grandparents) than it was for peripheral relatives (e.g., siblings, aunts and uncles).
In a third study, this interaction was replicated in an archival analysis of wills.
The implications of accounting for differences in relatives’ lineages in studies of kin investment are discussed.