Consanguinity

Consanguinity, or Kin, is the relationship existing between persons descended from a common ancestor. It cannot exist without a legal marriage. Consanguinity is either lineal or collateral. Lineal consanguinity exists between persons related to each other in the direct ascending line, as from son to father, grandfather, great-grandfather, etc., or in the descending line from great-grandfather to grandfather, father and son. Collateral kindred are those who, though they have the same blood derived from a common ancestor and are therefore consanguinei, do not descend one from the other. Thus brothers have the same blood and are descended from a common ancestor, but they are related to each other collaterally, and the children and descendants of each of them are all collateral kinsmen to each other. By the law of England, all persons related to each other by consanguinity or affinity nearer than the fourth degree of the Roman law are prohibited from marrying except in the ascending or descending line (in which the case can hardly occur in the course of nature).