Who counts as a parent for the purposes of filial obligations?

I argue that using a traditional biological account of parenthood causes problems for determining who counts as a parent for the purposes of filial obligations in alternative family structures. I then argue that a better way to understand parenthood is as a role. People who fill the role of parents are parents, regardless of their biological ties to a child. Next, I argue that children can have more than two parents and so can have filial obligations to more than two people. I then demonstrate that understanding parenthood as a role allows us to correctly account for who should be a parent in cases of adoption, surrogacy, and extended families. In the final section I discuss three related worries about allowing a child to have more than two parents.