Related for Yevamot 74:2

אמר אביי מנא אמינא לה דכל ספיקא לר' אליעזר בן יעקב כודאי משוי ליה

he had intercourse, and, similarly, when a woman with whom many men had intercourse does not know to which particular man her conception is due, the consequences are that a father will be marrying his daughter and a brother his sister, and the whole world will be filled with bastards,<span class="x" onmousemove="('comment',' Thus it has been shewn that, according to R. Eliezer b. Jacob, even persons of doubtful illegitimacy are described as 'bastards'. ');">²</span> and concerning this it was said, And the land became full of lewdness'.<span class="x" onmousemove="('comment',' [H] Lev. XIX, 29, Tosef. Kid. I. ');">³</span>

Shulchan Arukh, Even HaEzer