Epilepsy and impulsive behavior; any relationship?

Could be. Especially if you possess complex partial seizures. Discuss with your neurologist, but do not disregard possibility of medication adverse effect, especially if you are taking a Dopamine agonist.
I agree. The full . array of mental health & behavioral disorders & their possible internal &/or external causes are explained on: www2.massgeneral.org/childhoodepilepsy/child/mental_health.htm, which states "People with epilepsy are as much as 5 times more likely to have mental health & behavioral problems, with an incidence of 30 -50 %, as compared to 8.5 % in the general population." .