Prohibited Relationships

A marriage is deemed void where the parties are within a prohibited relationship (as per Section 23B of the Marriage Act).  A prohibited relationship is between a person and their ancestor or descendant, and between a brother and sister (whether of the whole blood or the half-blood).

For example, a marriage between a grandfather and his granddaughter is prohibited; however, a marriage between an aunt and her nephew, or between first cousins would be permissible.

To determine a prohibited relationship, adopted children are treated as if they were born naturally into the family.  This includes adoptions that have been annulled, cancelled or discharged.  In effect, a person who has been adopted has a prohibited relationship with their natural ancestors and siblings as well as any adoptive ancestors and siblings.