Report No. 90
Canon 1076
1. In the direct line of consanguinity marriage is invalid between all the ancestors and descendants, legitimate or natural.
2. In the collateral line, it is invalid up to the third degree inclusive, but with the understanding that the matrimonial impediment is multiplied only as often as the common ancestor is multiplied.
3. Marriage must never be allowed if there exists any doubt that the parties may be related by consanguinity in any degree of the direct line or in the first degree of the collateral line.