Was doing some work related research and found this is very gross & very sickly - yes you can legally marry your niece, or nephew or cousin ..... SICK SICK SICK!
Marriage to a relative
The Marriage Act prohibits people marrying:
These restrictions also apply to adoptive relationships even if these have been annulled, cancelled, discharged or cease to be effective for any reason (for example, a subsequent adoption order being made).
- an ancestor or descendant; or
- their brother or sister (whether whole blood or half-blood siblings)
This means, for example, that a person cannot marry their parent, grandparent, child, grandchild, brother or sister. However, (depending of course on the gender of the party) a person may marry their aunt or uncle, niece or nephew or ‘first’ cousin.