The Lycan Syndrome
Biology Made Simple - Lycanthropy
"Werewolfism" - Common fable, but I'm here to explain how it could happen: the "curse" would (most likely) be a type of retrovirus, which would remain dormant for quite a while. Said virus could be passed down by genetics (genetic disorder) or by exchange of DNA directly to the bloodstream (saliva, blood-transfusion, etc.). The virus (if the person was born with it) would begin to multiply, literally, as soon as the person was born. Over the years, the virus count would reach a maximum number in which it could live, and lay dormant. It would then have to be stimulated in one of the most extreme ways possible for a human to encounter: puberty.
Born with the Strand:</b> As the body begins to mature more, the virus may sense the changes, and become active, but is only "released" on the body's internal clock. If it's the usual "Once-a-month" strand of virus, it acts on, so-called, "PMS" time (Even in boys), although, it's also stimu