text: although the catholic church prohibits it,why do some people around the world marry their 1st cousins ? i'm speaking of people who are of the catholic faith. according to canon law 1091, consanguinity (blood relationship) in the direct line (father & daughter, grandmother & grandson, etc.) or in the indirect line (first cousins) is an impediment to marriage.  this impediment may be able to be dispensed by the bishop of the diocese.   with love in christ.