A man married a woman and he fathered children from her, then he discovered that she is his half-sister. What should he do?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

This man is obliged to divorce this woman immediately. Regarding his children; they will be traced back to him. One should have investigated and asked about her family lineage before marriage. May Allaah forgive all of us. Allaah Says (what means): {Prohibited to you [for marriage] are your mothers, your daughters, your sisters, your father’s sisters, your mother’s sisters,…}[Quran 4:23].