Unless the council shall by unanimous vote shall be recorded as part of its official proceedings, determine that the best interests of city shall be served, the following relatives of any elective or appointive officer are disqualified from holding any appointive office or employment during the term for which said elective or appointive office was elected or appointed; spouse, child, parent, grandchild, grandparent, brother, sister, half-sister, half-brother or the spouses of any of them. All relationships shall include those arising from adoption. This section shall in no way disqualify such relatives or their spouses who are bona fide appointive offices or employees of the city at the time of the election or appointment of said official.