御祖父さん[ojiisan] grandfather
御祖母さん[obaasan] grandmother
遠祖[enso] forefathers
開祖[kaiso] (sect) founder
外祖父[gaisofu] maternal grandfather

共同祖界[kyoudousokai] international settlement
教祖[kyouso] founder of a religious sect
元祖[ganso] originator
お高祖頭巾[okosozukin] kerchief worn by women in former times in Japan in cold weather, covering the whole head (except eyes)
始祖[shiso] founder

育ての親[sodatenooya] foster parents
育て親[sodateoya] foster parent
１等親[ittoushin] first-degree relative
仮親[karioya] adopted parents
近親[kinshin] near relative

近親婚[kinshinkon] consanguineous marriage
近親相姦[kinshinsoukan] incest
懇親[konshin] friendship
懇親会[konshinkai] friendly reunion
似非親[eseoya] distant disinterested parent