Who Shot J.R?

I don't remember actually ever watching Dallas growing up. But . . . I do know the theme song and performed it very well with my siblings while standing on the rock fireplace in the living room. We would stand and hum, dum de dum, whatever the tune. Hmm, why did we only do this when my parents weren't home? I have a feeling they didn't watch Dallas either - must have been older siblings?