Edward Heinlein, Catholic Encyclopedia (1913)
“ The above mentioned texts forbid marriage (1) in lineâ rectâ, with stepmother, stepdaughter, grand-stepdaughter, mother-in-law, daughter-in-law; (2) in lineâ collaterali, with paternal uncle's wife—aunt— (some versions include also maternal uncle's wife) , with sister-in-law, except in those cases where the lex leviratus obtains, with wife's sister as long as the former is living. Be it remarked here that the Jews considered the relationship existing between the wife and her husband's family as of a closer nature than that between the husband and his wife's family. ”
