Yes, it is possible. Sponsor is under the Family Class of Visa and since Canada as a country emphasises familial bond, you can be sponsored if you are a conjugal partner, common law partner, parent or grandparent. If you are a child of a permanent resident, you are also eligible to be sponsored. In circumstance of siblings, only if the said sibling is not older than 22 years old. Then such sibling can accompany the sponsored party.