What is marriage without dealing with and learning to love the weird quirks your significant other has? In the new documentary Prince, Son, and Heir: Charles at 70 — which aired on BBC One on Thursday, Nov. 8 — Prince Harry hilariously revealed he has one major at-home obsession that bugs his wife, Meghan Markle, to no end.

“My wife certainly goes, ‘Well, why turn the lights off? It’s dark,'” Harry said in the film. “I go, ‘We only need one light, we don’t need, like, six,’ and all of a sudden, it becomes a habit.” Looks like this is one of Harry’s silly quirks that Meghan, 37, is going to have to get used to!

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Harry, 34, said he learned the energy-saving habit from his father, Prince Charles, who is a “stickler for turning lights off.” This comes as no surprise considering Charles has rallied for environmental conservation for decades.

“That’s now something that I’m obsessed with,” the Duke of Sussex admitted. In fact, he is not alone. His older brother, Prince William, also confessed that the pair shares the same obsession. “I’ve got serious OCD on light switches now,” William said. “Which is terrible.”

We assume Charles, 69, is happy with the royal duo following in his eco-friendly footsteps for the sake of his grandchildren. Though the father-of-two is over-the-moon about his fourth grandchild on the way, he recently revealed he fears for the world that they will live in.

“I am about to have another grandchild actually,” Charles said, according to The Telegraph. “I suspect quite a few of you may too have grandchildren or will do soon. It does seem to me insanity if we are going to bequeath this completely polluted, damaged, and destroyed world to them.” He added, “All grandchildren deserve a better future.”

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Conserving energy by turning off lights isn’t the only thing that resonated with William and Harry. In the documentary, we also learned about the times when the two brothers would go out with their father to pick up trash. “He took us litter picking, when we were younger, on holiday,” William, 36, revealed. “Both of us thought, ‘This is perfectly normal, everyone must do it.’ We’re there with our, basically, spikes, stabbing the rubbish into black plastic bags.”

Perhaps Harry and William were inspired by Charles and their late mother, Princess Diana. “He’s done an amazing job. Without telling us what we should be doing or the direction we should go in, he’s just let us learn from the nature of the job, learn from him, learn from mummy,” Harry shared. We’re not sure how long Harry’s obsession with turning lights off at home is going to last, but we’re guessing his children will be taught to respect the environment just like he was!

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