The 'Wolf Is Getting Married' singer – who has previously revealed a love of the drug – admits her children, Jake, 24, Roisine, 15, Shane, seven and Yeshua, five, do not know she enjoys smoking dope because she does so in secret.
She said: "Oh the kids don't know I smoke dope! I just sneak down the garden. But kids now, they're very anti-drink and drugs and cigarettes."
Sinead has come to an agreement with her daughter Roisine that she will get drunk for the first time in the presence of her mother so she can assess how she reacts.
She added: "Roisine is 16 in March and I have an agreement that the first few times she drinks, she'll do it at home. So she knows whether she's the type who's going to have her knickers round her ankles after a bottle of vodka walking down the high street."
However she admits she has a stricter view of her children smoking weed than she has on herself, because she is worried she would "lose them down a tunnel".
She told The Word magazine: "With the older one and his mates, yeah, they were smoking dope but they were 18, 19. And I was more worried they'd be out getting arrested. Which has happened.
"So I just said, 'I'm going to pretend I didn't see it and just go down the garden and don't get arrested.' But now I wouldn't allow it. With teenagers you can lose them like that, down a tunnel."