This could be for child support/divorce reasons, court/criminal issues, etc.  

Adult, child, pet makes no difference and not relevant to Fair Housing.

My parents owned real estate when I was just a child which eventually I had a early head start of learning investing skill.

Nobody (accept me and a few others) tells their small child to grow up and start a business.

I would write down principal, I'd ask if that included taxes, "does that include insurance", do you have an HOA, is there a second loan on the house, a HELOC or any unpaid child support liens, and then I would say, very casually "about how much will it take to bring the house current?

When prospective tenants suggest this arrangement, I tell them that the one who is not financially responsible will be more or less like a child on the lease.

I am married with 3 boys (4,2,and a newborn).

I've done a bit of research and from what I understand this is allowed because I am his child.

Many tenants who attempt to take their slumlords to court because rats were sharing the crib with their child or the slumlord decided not to heat the building in January, are faced with eviction proceedings.

On the one side the tenant and her husband and child have lived there for 3 years and are currently on a month to month lease.