U2 singer Bono has revealed he has a half-brother, whose existence he was unaware of for decades.
"I have another brother, whom I love and adore, who I didn't know I had," he told BBC Radio 4's Desert Island Discs.
The singer said he found out about his half-brother in 2000, adding that he is "at peace" with it.
The 62-year-old told host Lauren Laverne that his mother Iris, who died in 1974, did not know her husband had a child with another woman.
"It's a very close family," Bono said, "and I could tell my father had a deep friendship with this gorgeous woman, who's part of the family, and then they had a child. And this was all kept secret."
After Bono found out, he spoke to his father Bob before his death in 2001.
"I asked him, did he love my mother, and he said yes," he recalled. "And I said, how could this happen, and he said, 'It can', and that he was trying to put it right.
"He wasn't apologising, he was just stating, these are the facts. And I'm at peace with it."
Asked whether his mother knew, Bono replied: "No, nobody knew.
"My father was obviously going through a lot, but partly his head was elsewhere because his heart was elsewhere."
The singer also has an older brother called Norman.
On the programme, Bono discussed the death of his mother, from a brain aneurysm when he was 14, and how her death had a huge impact on his family.
"It's pocketbook psychology but I immediately just found another family - I formed U2, I found Ali [Hewson, his wife], it happened quite quickly," he said.
Bono described his relationship with his father as "complicated", adding: "I'm sure I was hard to deal with.
"And he was coping with a lot. He didn't know quite what was going on. And I subsequently understood he was coping with other stuff."
Bono, who plans to release an autobiography later this year, rose to fame in the early 1980s and became one of the biggest rock stars on the planet.
The band's hits include Vertigo, Beautiful Day, One, With Or Without You and I Still Haven't Found What I'm Looking For.
He wrote many of the group's most successful songs, as well as becoming known as a human rights activist.
Desert Island Discs is on Radio 4 at 11:15 BST on Sunday, and on BBC Sounds.