He had a DNA test and it turned out he and his wife were siblings

The woman, who was born with a sperm donor, had a DNA test done with her husband years ago. The test results revealed that the two had the same biological father and were half-siblings.
"At first I thought it was a mistake. But as we investigated, we learned that my husband was also born via donor and he had no idea about it," said the woman, adding that this situation made her question everything she knew about their family structure.
The woman also stated that she has two children from her husband.
Tele1