@Reed Starkey this is what I found out. Age is not a protected group.
1.You cannot refuse to rent to someone for the following reasons:
a.Race
b.Color
c.Sex (gender)
d.Religion
e.National origin
f.Disability
g.Source of income (public assistance)
h.Familial status (children under 18 with parent, pregnancy)
i.Sex orientation
j.Gender identity.
2.You can refuse to rent to someone for any other reason or no reason at all.
3.If an applicant does not have any of the protected qualities, then they have no basis for claiming unlawful discrimination.
4.The areas of risk are when you are dealing with someone that has one of these qualities. If you refuse to rent to them, then they can claim that the refusal was made on the basis of their race or religion and was an unlawful act of discrimination. In response you will need verifiable proof that the refusal was based on something other than the race or religion. This is where applying your rental criteria comes in as a defense.
Occupancy limits. There is nothing unlawful about setting an occupancy limit – unless it is a pretext for discriminating against families. Therefore, you can limit the number of occupants in this manner:
The number of occupants in this apartment is limited to X, except in the case of a family, in which case the number of occupants are limited to two persons per room.