Well, I watched my brother play Super Mario Brothers on the NES and I was fascinated by it, I was I think 4 or 5. He even let me play with him by swopping the controller back and forth after each level.
That, and where I grew, before I moved away due to me getting super sick in the winter, we had a basement that was used for when there was a tornado warning. So, to keep me from being bored out of my mind, I would play games with my brother, or by myself. We also had a computer, an Apple e2, that had some games on it, and I would play those since I was the only kid that played computer games.