Michael Jackson was the biological father of his three children, the pop star's brother said.
Tito Jackson said the children all bore a family resemblance, with Blanket - whose real name is Prince Michael II - having the same eyes as the singer.
He told the Daily Mirror: "They are all his children. Blanket is Michael's, I can tell. Those eyes don't lie. Them eyes are Michael over again. I see a lot of Michael in him."
He also dismissed suggestions that the children were too pale to be Jackson's.
"Just because they look white doesn't mean they are not his. Prince looks just like my grandfather. There's no question they are Michael's. They are 100 per cent his...They remind me of me and my brothers when we were growing up," he told the newspaper.
But he said nobody, including himself, knew the identity of Blanket's mother, describing it as the "million dollar question". Blanket was born to a mystery surrogate mother the singer never even met.
Despite growing up in the glare of the media spotlight, the children were all "very, very normal," Tito, 55, added. He said they enjoyed wearing masks when they went out and that they knew that they and their father were famous.
His comments came as pictures emerged that were said to depict needle puncture marks on the star's ankles and a large wound on his right shin - thought to have been caused by his injection of drugs.
Meanwhile a magazine obtained video it said shows never-before-seen footage of Jackson's head catching fire during filming of his 1984 Pepsi advert.
Jackson suffered severe burns after a pyrotechnics accident set his hair and scalp alight. The video on Us Weekly's website showed the moment Jackson's hair caught on fire and the top of his head became engulfed in flames.