The Duke of Sussex has revealed to the BBC that he was picked on at Eton for a habit he picked up from his eco-friendly father.
Appearing on a documentary marking his father's 70th birthday Harry was shown footage of Charles warning about plastic pollution in 1970. Responding to the clip, Harry said: "I used to get taken the mickey out of at school for just picking up rubbish.
"When you go for walks anywhere, if you see something, it stands out, you pick it up.
"Before you know it, somebody [says], 'What are you doing?'
"I've literally done this because I am programmed to do it because my father did it. And actually, we should all be doing it."
Expanding on his father's legacy, Harry added: "He's done an amazing job, without telling us what we should be doing or the direction that we should go in.
"He's just let us learn from the nature of the job. Learning from him. Learning from mummy."
Harry's older brother, Prince William, who also appeared on the documentary, elaborated on the family's love of refuse collection: "He [Prince Charles] took us litter picking when we were younger. On holiday!
"We were in Norfolk... And again, both of us thought this is perfectly normal, everyone must do it.
"We were there with our spikes stabbing the rubbish into black plastic bags."
Prince Harry recently launched a sustainable travel initiative called Travalyst, which aims to "encourage sustainable tourism practices" across the industry.
Harry said: "Sometimes the scale of the conservation crisis feels overwhelming and that individual actions can't make a difference.
"I've certainly felt that - but I've learned that we cannot dismiss the idea of trying to do something, just because we can't do everything."