[SCAEUOLA libro primo regularum. ] §23.2.54.prEt nihil interest, ex iustis nuptiis cognatio descendat an uero non: nam et uolgo quaesitam sororem quis uetatur uxorem ducere.
[SCAEVOLA, in his first book of Rules.] And it makes no difference whether the relationship descends from a lawful marriage or not: for anyone is forbidden to marry even a sister born out of wedlock.