It is widely accepted that depression shows a tendency to run in families. This is partly due to genetic influences--and the subject has been covered in recent reviews. This article, therefore, does not aim to recapitulate the genetic evidence but rather aims to elucidate the mode of transmission, to achieve an understanding of relevant gene-environment co-actions and interactions, and to describe attempts to identify and localise major genes.
The genetics of depression: current approaches. Publishing Authors By Initials