The soon-to-be record breaker was earlier said to be "fuming" that his 14-year-old daughter was 11 weeks pregnant because she was due to start her school exam courses.
But neighbours said he was in fact celebrating because more state benefits would be given to his family - and said he had bragged about "making a fortune" on selling his story.
The man - whose identity is being kept a secret to protect his young daughter - is now said to be in negotiations to sell his family's story to a Sunday newspaper.
But before talks with the tabloid had begun, the man said: "It’s like history repeating itself".
"I quite like the idea of being the youngest grandad in Britain, but at the same time I’m fuming that she is pregnant.
"I know myself how tough it is being a teenage parent and now she has to go through the same thing.
"However, we’re all going to stand by her and we will welcome the little one into the family. She is very young, but she was determined to keep the child. We were not going to force her into doing anything else. We don’t want her to hate us."
He added: "I don’t feel like a grandad. I’ve not got grey hair and my hearing is top notch."
But a mother in her 30s who lives nearby said: "He just wants it to be all about him. He should realise how serious it is.
"If it was my daughter pregnant so young I certainly wouldn't be singing about it."
Speaking from his home in South Wales, the man admitted he became a father back in 1996 when he was just 14.
He said his own mother, who is 47, is excited about the prosepct of being a great-grandmother.
"She was 18 when she had me," he said. "She was shocked when I told her the news, but she is happy now.
"Her own mum is alive, and so too is her grandmother, who will become a great-great-great grandmother.
"There can’t be too many families with six generations alive at the same time."