Are confusional migraines genetic or de novo?

Rarely genetic. Acute confusional migraine is diagnosed after excluding other causes of confusion like seizures, strokes, tunour, infection, drugs--- it is more common in children and after mild trauma very few citation in literature link confusion with migraine and genetic mutation-- more genetic is episodic ataxia with confusion, hemiplegic migraine.
Good question. It is not settled yet. More important , let your internist know, possible referral necessary.