Responses
yess that's exactly the point. so grandma and the sensei is not related by blood. hence the papa said hes glad their situation is the same (papa with maika and sensei with grandma)
Sensei can be grandma's child, just not her's with husband. Or her husband is the father and sensei has a different mother. B and 0 can lead to: BB, B0 and 00. Sensei can very much be A0. So that is up in the air.
If the mother and the husband were both B, their children can only be B or 0. Right? This bothered me so much x.x