Photo: Kevin Mazur/WireImage

Rod Stewart children

Rod Stewarthad the talk with his teenage son, but it didn’t go as expected for the father of eight.

The 76-year-oldTears of Herculesmusician tells PEOPLE that he had a funny moment with Alastair, who turns 16 this month, when he sat him down to talk about sex.

“My 15-year-old is dating girls, so I had to give him a sex lesson. I just told him what he should and shouldn’t do, but he’s on top of it. He was like, ‘Dad, I’ve got the internet. I know everything,’ " says Stewart.

“I have to be several different fathers because of the different age groups of my kids,” explains Stewart. “You really have to treat all of them as individuals with individual problems.”

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Rod Stewart and Penny Lancaster.Dave J Hogan/Getty

penny lancaster and rod stewart

The key to his 14-year marriage with Lancaster, Stewart tells PEOPLE, isintimacy: “I’m not talking about sex, but a kiss and a cuddle and a hold. Penny and I do that every morning. We hug each other — sometimes in bed, sometimes out of bed, all throughout the day. It’s a wonderful relationship. Lucky geezer, aren’t I?”

“I couldn’t ask for anything better,” he adds. “What makes me happiest now is seeing all my kids and my wife with big smiles on their faces.”

For all the details on the lessons Rod Stewart has learned about love and life, pick up the latest issue ofPEOPLE, on newsstands now.

source: people.com