Available evidence suggests that migraine pain is one symptom of several to many disorders of the serotonergic control system, a dual hormone-neurotransmitter with numerous types of receptors. Two disorders — classic migraine with aura (MA, STG) and common migraine without aura (MO, STG) — have been shown to have a genetic factor. Studies on twins show that genes have a 60 to 65% influence on the development of migraine (PMID 10496258 and PMID 10204850 ). Additional migraine types are suspected and could be proven to be genetic. Migraine understood as several or many disorders could explain the inconsistencies, especially if a single patient has more than one genetic type.