Bono will release his memoir in just a few months, but it seems that the U2 frontman is teeing up fans for a few startling revelations in the run--up to its publication.

The Dubliner was on 'Desert Island Discs' yesterday and revealed during a conversation with host Lauren Laverne that he and his brother Norman have a half-brother as a result of their late father Bob's affair.

The 62-year-old only found out about his sibling in 2000, a year before Bob died, and both the child and the affair were kept secret from his mother Iris, who died suddenly when Bono was 14.

"I do have another [brother] who I love and adore,” he said, adding that learning about his half-sibling's existence helped him to understand his father's behaviour.

"My father was going through a lot. His head was elsewhere because his heart was elsewhere," he said. "I could tell my father had a deep friendship with this gorgeous woman who was part of the family and then they had a child which was all kept a secret. Nobody knew.”

He said that he had had challenging conversations with his father before he died. “I asked him, ‘did he love my mother?’," he said. "He said, ‘Yes’. And so I asked him ‘how could this happen?’ and he said, ‘it can’, and that he was trying to put it right, trying to do the right thing. He wasn’t apologising, he was just stating these are the facts. I am at peace with it."

In the same interview, he spoke about the criticism U2 face for moving their business abroad in order to pay less tax. "At the root is a false idea that if you are tough-minded in your activism you somehow have to be soft-minded in your business," he said. "It would be immoral to be dismissive of those things. It is actually your fiduciary duty … to control costs. There are lot of reasons not to like our band and this is not one of them. We pay a lot of tax and are very proud to pay tax. So it is, like, really?"

He also mentioned the recent flak he'd received for the poem that he'd written about Ukraine, which was read out by Nancy Pelosi in the US House of Representatives.

"I write limericks sometimes for the Paddy’s Day event," he said. "It took 10 minutes, it was trying to be a satire, funny and the speaker of the house, who is an incredible woman, instead of saying ‘limerick’, said it was a poem and so people thought it was like Seamus Heaney.

"I deserve a slap. Every singer in a rock and roll band is going to say the wrong thing. But that poem business is ridiculous. It was just a limerick.”

You can hear the full interview here.