Culture is a strange thing. I would be interested in the viewpoint of Japanese women who might explain this in a way that makes some sense. I am guessing it has to do with family name rather than the “blood line.” American culture is much like that.

The Jewish linage is passed through blood. That is how prophecy could predict that Christ would be born of the line of David. Mary was the blood line to David and Christ was born without ability to sin since that is passed on by the father.

We only have our American viewpoints, and so everything we consider is considered through that lens. I wonder what the perspective is of women in Japan.