I will restate my position so those of you with bad parenting skills that do not hold your children responsible for their behavior can get with the program. There is nothing wrong and many LL’s do require that any member of the household who has reached the age of 18 or will reach the age of 18 during the term of the lease provide a social security number. Unless you can provide some law that in Mass this practice is illegal, you can look elsewhere for a place to live.
BM, I would not take your “EXTENSIVE” research to serve as an indicator as to what is legal in the state of Mass. In fact, I always tell new landlords that the first thing they need to learn is to disregard anything their tenants tell them about rental laws. This is sound advice since most of what tenants claim to be the law is either a myth passed down by other tenants, or just pure misinterpretation of the law.