While it is well-known that parents influence their offspring via the genetic material they pass on, it is becoming increasingly recognized that parents can also influence their offspring via non-genetic mechanisms. To date, studies have focused on the influence of a single parent on their offspring, despite the biological reality that mothering and fathering co-occur in most organisms. The goal of the proposed project is to examine the joint influence of mothers and fathers on offspring behavior in threespined sticklebacks (Gasterosteus aculeatus), a small fish in which the father is solely responsible for parental care. One of the advantages of studying sticklebacks is that the non-genetic influence of mothers and fathers on offspring is disassociated in time and occurs via different mechanisms: mothers influence offspring early in development via material in the eggs, while fathers influence offspring via their parenting behavior. The proposed studies will reveal whether non-genetic parental effects on offspring behavior can be adaptive, and help to prepare offspring for survival in a dangerous environment. In the spirit of this grant, a public outreach project with a local Boys and Girls Club has been initiated to study wildlife behavior with 8-10 year-old children, many of whom have been affected by the issues that are studied in the grant (foster care, adoption, differences in parenting styles, etc.), and who have had few opportunities to engage in science. The end result of this collaboration will be a handbook for basic behavioral experiments that are appropriate for this age group. The proposed activity will provide training and outreach opportunities for many undergraduates, a graduate student and one Postdoc, Understanding how mothers and fathers combine to shape the behavior of their offspring in sticklebacks can be used as a model for the influence of parents on offspring in other species, including humans.