Renting out a self-contained unit in your own home is treated no differently than renting out an apartment in a large building, a condominium or even a whole house. The tenant is protected by both the Residential Tenancies Act (RTA), and the Ontario Human Rights Code (OHRC). That being said, it is a breach of the OHRC to rent a unit and demand that there be “no children” allowed.
You can read more about the protected grounds and areas under the Ontario Human Rights Code at the following website: http://www.ohrc.on.ca/en/ontario-human-rights-code