In the general application form, 'dependents' means your children; you don't have any, so don't list anyone there. For most of the forms, CIC defines 'family member' as your spouse or common-law/conjugal partner and your children. They do not mean 'mother, father, aunts, uncles, cousins, grandparents, etc.'
However, for the Additional Family Information IMM 5406, the applicant has to list his or her spouse or partner, his or her parents, his or her children, and all siblings, including step- and half-siblings. List them all, even if they are already Canadian citizens or PR, and even if they have no intention of coming to Canada. These people do not need medicals or immigration photos (except for any dependent children).