consanguinity

Latin: con, with; sanguis, blood

Blood-relationship, and a diriment impediment to matrimony if within certain degrees. It is of two kinds: relationship in the direct line, which means ancestry and descendants (parents, children, grandchildren, etc.), and for this kind of consanguinity no dispensation can be given; and in the collateral or sidewise line, in which no dispensation can be granted for the first degree (brother and sister), this being forbidden by the natural law. First cousins are of the second degree, second cousins of the third degree; and for these relationships dispensations may be granted.