NY Domestic Relations Law prohibits marriage between
sibs, ancestors and descendants, uncle and niece, aunt and nephew.
It does not prohibit marriages between first cousins. I cannot say
what the law provided in 1909.
A marriage between prohibited persons is void if contracted
in NY, or in any place where it is void. If a marriage between prohibited
persons, such as uncle and niece, is contracted in a state where such
a marriage is valid, NY will treat the marriage as valid.
U. of San Diego Law School, 5998 Alcala Park, San Diego CA 92110-2492