Sarah Palin's future son-in-law and father of her first grandchild has a mother with a sordid past. Sherry Johnston was arrested in December for allegedly selling drugs.

Sherry Johnston, the mother of Levi Johnston, the father of one-time VP candidate Sarah Palin's teenage daughter Bristol's baby, is speaking out. She tells People she was prescribed OxyContin as a painkiller after having a hysterectomy eight years ago.

She says the surgery and further complications forced her to give up her career as a hairstylist because she couldn't comfortably stay upright. "I am disabled," she says, adding "I have been trying for years to deal with the pain. I have a medical pump inside me." As for the pending charges against her, she tells the mag "I'd rather not comment any more but it's not everything that they're saying."

In December, she was arrested on charges she was selling the drug. She plead not guilty at a January 5 arraignment in Palmer, Alaska.

As for being a grandmother to Tripp Easton Mitchell Johnston, son of 18-year-olds Levi and Bristol, Johnston says "I'm very excited. Absolutely I think he looks just like Levi."