Rejecting a family from living in a one bedroom apt

[Jered Sturm]

I recently purchased a building with one bedroom apartment so am asking this question hypothetically so that I can approach it correctly if it ever comes up in my screening. Can you reject an applicant applying for a one bedroom apartment based on how many people would have to share a bedroom? For example if a single Mom has 4 kids ages 17,10,8,3 am I really legally obligated to accept them to live in a one bedroom 500 sqft if they meet my standard requirements? Or how about 4 adults saying they want to share the bedroom. I guess my question is can I discriminate against children or number of residence if the building is unfit for families. Where is the line drawn?? It's odd if a mom dad and 16 year old son share a bedroom. Could I deny over this? But what makes that legally any different than a mom dad and a infant son sharing a bedroom? Any opinions or advice would be appreciated.