Home occupations conducted solely by permanent residents of the household shall be permitted, provided that there shall be no change of any kind in the residential character or appearance of the dwelling or property, nor any perceptible indication immediately outside of the dwelling unit which would suggest the presence of any home occupation. Such occupation shall be one which is normally and customarily conducted within a residence and shall be clearly incidental and secondary to the principal use of the premises for residence purposes. Home occupations shall not include residential professional offices, said offices being conditional uses as defined and regulated pursuant to § 20-17.