It is actually pretty simple, it sounds kind of complicated but a lot of it is from the flavor.
Mafia orphanYou were raised by adopted parents who found you on the street when you were two. They raised you as if you were their own, but they were always disturbed by the tattoo on your back. It depicts a man's body with the legs totally gone, and every other finger cut off. You also have another tattoo, that depicts a family of X members in silhouettes, one of them is clearly you but the rest are indistinguishable.
When [example murder victim] was murdered, his body was found with no legs and every other finger cut off! The news release says the authorities are certain the murder was the result of organized crime. That means surely you must be a long-lost son of a mafia member.
You are allied with the mafia. You donothave the usual mafia power of murder. You win when all people in town are dead except for players allied with the mafia, or when nothing can prevent the same. You do not know who the other mafia allied players are, and they don't know that you are their ally either.
Every night, you choose to either 1) steal a DNA sample or 2) send a letter with a photo of your tattoo.
If you decide to steal a DNA sample, you send the moderator a name of a living player. That person is not informed of this action. The mod will return whether or not that player is a member of your mafia team.
If you decide to send a letter with a photo of your tattoo, you send the name of the letter's recipient to the mod. The mod informs that player that you are a Mafia Orphan. If the letter recipient was a member of your mafia family, all members of the mafia receive the same information, and the mod automatically send back your family's jubilant reply, with all their names signed. They also mail you a gun. You lose your former powers (1 and 2) and become the same exact thing as a mafia goon every night onward.
If the letter recipient was not part of your mafia family, you will receive no reply letter. Note that the player would from then on know you are mafia.
Tracing your genealogy and meeting your family is extremely important to you. If all of your X teammates die, you will immediately commit suicide in grief, and instantly lose.