Oop. Looks like I'm memetically contagious. Ordinarily I'd say that with the Constantine family, sometimes it's easier just to go back to a previous member, since there seems to be a magically talented jerk in each generation. However, John's granddaddy was one of the few non-magically talented ones and is the only real candidate I can think of for the time frame in question.

(Unless he had a brother we just never saw in the comics, of course.)