Here's what the law in New Zealand says:
FORBIDDEN MARRIAGES
1. A man may not marry his
(1) Grandmother:
(2) Grandfather's wife:
(3) Wife's grandmother:
(4) Father's sister:
(5) Mother's sister:
(6) Mother:
(7) Stepmother:
(8) Wife's mother:
(9) Daughter:
(10) Wife's daughter:
(11) Sons' wife:
(12) Sister:
(13) Son's daughter:
(14) Daughter's daughter
(15) Son's son's wife:
(16) Daughter's son's wife:
(17) Wife's son's daughter:
(18) Wife's daughter's daughter:
(19) Brother's daughter:
(20) Sister's daughter.
2. A woman may not marry her
(1) Grandfather:
(2) Grandmother's husband:
(3) Husband's grandfather:
(4) Father's brother:
(5) Mother's brother:
(6) Father:
(7) Stepfather:
(8) Husband's father:
(9) Son:
(10) Husband's son:
(11) Daughter's husband:
(12) Brother:
(13) Son's son:
(14) Daughter's son:
(15) Son's daughter's husband:
(16) Daughter's daughter's husband:
(17) Husband's son's son:
(18) Husband's daughter's son:
(19) Brother's son:
(20) Sister's son.
3. The foregoing provisions of this Schedule with respect to any relationship shall apply whether the relationship is by the whole blood or by the half blood. . . .
4. In this Schedule, unless the context otherwise requires, the term "wife'' means a former wife, whether she is alive or deceased, and whether her marriage was terminated by death or divorce or otherwise; and the term "husband'' has a corresponding meaning.
Mackin