The 74-year-old — who has been married to “Miss Kay” Robertson since 1966 — only found out about his daughter a few months ago, after the woman underwent DNA testing and then reached out to his children, Robertson and kids Al, Jase, Jep and Willie said on his “Unashamed” podcast.

Al explained that he and Jase each received letters from a woman named Phyliss three months ago claiming to be his sister.

“So basically, it was from a woman who said that by a DNA search, she thinks that Dad might be her dad,” Al said, adding that he had at first “dismissed” the letter because the time of the affair was after Phil had become a Christian in the ’70s.

“There was a clear dividing line for Dad.”

But Al and Jase decided to look into the claims with the help of their podcast producer.

“I started thinking, ‘There’s a 45-year-old woman out there who doesn’t know who her dad is, and she’s looking,’” Al said, “and I thought, ‘Even if it’s not Dad, she needs to know it’s not Dad.’”

The producer called Phyliss and talked to her and realized her intentions were genuine.

“She’s not out for anything,” he told Al. “She’s a Christian.”

Al and Jase decided to tell their parents about the letters, which prompted Phil to take a DNA test.

“When you’re praying about something like this, there’s a truth that’s already there,” Al said. “You’re just praying for truth to be revealed.”

It resulted in a 99.9% match, they said.

“Bring her on down,” Phil said upon getting the news.

The family met Phyliss and said their podcast audience would get to meet her soon.

“It’s a pretty cool explanation of redemption, reconciliation, love,” Phil said. “As it turns out, 45 years you have a daughter you don’t know about, and she has a father she doesn’t know about. Forty-five years doesn’t sound like very long, but you say, that’s a while. So finally, after all those years, we come together.”