As far as my earliest exposures to sci fi goes, I had never really thought about it before but I always was really a sci fi fan and I never knew it. My dad was really into Star Trek The Next Generation and we watched it every night growing up. What I loved about it was that it could be so creative and anything was possible. There were always new alien-looking people coming on board and causing problems, Vulcans could mind-meld, whatever that meant, Commander Riker could hook up with hot babes on the holodek, and the crew transported themselves up and down to planets. It was great.
Some other sci fi that I watched included:
Out of this world.
Would you like to swing on a star? Carry moon beam home in a jar?
I always had a crush on Evie Garland, and a secret hope that when I press my two index fingers together that I too would be able to stop time. It never worked though. I watched this tv show every single day for years. Evie's father was an alien, but he died before she was born. She discovers her secret stopping-time power and learns how to live life without abusing her power.
Teenage Mutant Ninja Turtles
My favorite turtle was always Donatello, the inventor, because he was nice and he was smart. You know the story, four little turtles are in a sewer when some toxic ooze is poured into the sewer and they turn into lean green fighting machines. Splinter, their sensai, is a rat/human because of the ooze but he teaches the turtles martial arts and they go around fighting crime. This was my ultimate favorite thing to watch.
I definitely remember watching E.T. and Flight of the Navigator a hundred times or so growing up. Also, I recently watched Close Encounters of the Third Kind and it turns out that I had seen that one before when I was growing up. I remembered so much of the movie while I was watching it but hadn't recalled it until then. But you know, I watched Aladdin and Lion King and stuff like that too. I didn't know that I was going to be a sci fi fan until very recently.
But movies always played an important role in my family. When someone expressed interest in hanging out, you might hear us reply "what movie do you want to watch?" Stephanie had to get acclimated to this. She would say that she wanted to hang out and when I popped the movie in she would be confused. I learned that she wants to talk when she says she wants to hang out.
Another anecdote: I never knew that my dad was wildly into sci fi when he was growing up too. When he first started reading my beerandscifi blog he was very surprised that I had somehow subconsciously picked up his tastes. He has seen most of the movies I've seen and a lot more of those obscure 60's and 70's movies. Those are generally my favorite ones to watch.