>>You have to look further into the subclades. J2 is of course older than J2a1. J2a1 seems to be more common around the Mediterranean, so we could expect an Italian or Greek origin for them. My O'Brien ancestry connects with Montgomery by way of marriage with a MacCarthy. This traces back to Arnulf "Cimbricius" Montgomery, supposedly of Calvados in Normandy. Assuming the Y-DNA is of Greek origin, my guess is that it was transferred to La Tene Celts in Gaul before the arrival of the Romans in Gaul. Sent from my iPhone