1
parentesco;consanguinidad
1
blood relationship;consanguinity
正直なところ、その当時の僕は血縁がどうとか、続柄がどうとか、そういう話はまるで理解出来ちゃいなかった。
Truthfully, at that time, I didn't have the first idea about such talk: family links, blood relations or whatever.
2
blood relative