>well biology is kinship-- and they use the same word for people who have the same degree of 'common genes' even if they didn't know about genitics.

my neices and nephews and grandchildren all share the same amount of kinship.

Yeahbut®, male and female cousiins share precisely the same degree of kinship and yet Italian distinguishes between them. So it's not about using the same word for those with the same degree of kinship.