Since countries where Christianity is believed have a monogynous system, a female-line royal family member often ascended to the throne and started a dynasty due to the discontinuity of male-line.
キリスト教圏は一夫一妻制なので、どの国でも歴史上、男系男子の断絶により女系の王族が即位し、新たに王朝を開くということがしばしばあった。