The skin on your hands and feet possess incredibly strong and microscopic suction cups. These are not visible to the naked eye, but can be employed to stick to a surface if it is reasonably smooth. The suction action is strong enough to support your weight and up to an additional 10 Kg per point of this trait.
This gives you the ability to scale walls like a spider. You do not need to perform any skill checks for climbing unless you are being disturbed or attacked and you can scale even smooth skyscraper glass walls.