[RTyokohama]

*子 comes from Chinese.
*子 is honorific title, like 孔子, 孟子
It was used well in ancient Japan for man, too.
for example 聖徳太子, 小野妹子

before Meiji era, *子 is used for woman but that is for court noble.
in Meiji era, every people became to use cognomen.
then, many people named *子. This trend continued until 1945.