Anthropology, 210 (Response for Chapter 7)

Your social analysis of the "mother" and "father" assignment is very valid, but I'd like to point out that there are times that adopted children have felt a sense of not belonging with their caregivers.  The definition of "mother" and "father" can be brought back to the nature versus nurture argument, where sometimes people will assign these roles to people who they feel fill those roles, be it within their household, outside the household, or even a figure they don't have true intimate ties with.  It's also variant between societies for the emphasis placed on parental figures, for instance, how some groups have communal caregiving, shared elders, and hold the genetic history in high regard.  These values would affect how a child would view themselves and their parental role assignments.