Consanguinity

Their degrees of consanguinity and alliance are very strange; for being thus akin and allied to one another, we found that none was either father or mother, brother or sister, uncle or aunt, nephew or niece, son-in-law or daughter-in-law, godfather or godmother, to the other; unless, truly, a tall flat-nosed old fellow, who, as I perceived, called a little shitten-arsed girl of three or four years old, father, and the child called him daughter.

Source: tatoeba (12115400)

1776, United States Declaration of Independence They too have been deaf to the voice of justice and of consanguinity.

Source: wiktionary

At Isabella's earnest request, he took both her and the child on board, for the single hour which remained to the voyagers, to the satisfaction of all parties, and it seemed as if the long-drooping flower had already revived beneath the genial smile of consanguinity, and the very tears she had shed were sweet and grateful, refreshing the bosom moved so tenderly.

Source: wiktionary

The Mongrel Virginians was similar to other eugenic family studies in its method and mode of argumentation, but its intensive focus on "race mixing," rather than consanguinity, represents a marked departure from the previous studies.

Source: wiktionary