A 60-year-old mother from Plymouth agrees with not giving up on the child. Her son is now 24 and lives in Wales. He began smoking cannabis on a family camping holiday at the age of 15. "He doesn't like to come back to Plymouth now, because many of his old friends are still in their bedrooms, smoking dope. It's a nonsense that this is not an addictive drug, a nonsense. I think he felt very guilty and knew he was throwing these precious years down the drain.
"I pinned up articles in his bedroom, talked to him and talked to him. It was a four-year nightmare: he stole his sisters' pocket money, he frightened his sisters and he would kick their doors in to get money or in rage. I had thought at first 'OK, he's a 15-year-old boy, he's going to dabble' – I was so innocent at first."
But she believes she was right to wait it out until her son got fed up of wasting his life. "Don't throw them out," she said. "Just love them, give them nice food, make sure they know you are there for them. Never give up on them and they'll come back to you."
Cannabis: a history