The American Association of Notaries reports that most jurisdictions do not have a specific ban on notaries notarizing family members' documents but that it is not a good practice to do so. Notaries are banned from notarizing their own documents or documents that they have any interest in.
Caution is needed because the probability of benefiting financially from a transaction by a family member is high. This probability increases the more closely a family member is related to notary. Even in cases where there appears to be no possible way to gain financially, it is recommended that notaries do not notarize documents for family members, reports the American Association of Notaries.