Why are these slides a funny color?

I've been scanning in old slides that I got from my maternal grandparents. It's been fun to have more family photos from long ago, as I have very few photos from that era. But I've also learned the importance of color correcting these slides. When they are scanned in, they have a colored cast that is quite distinctive and makes them look dated. I have been using the color correction tool in Photoshop (I use AutoCorrect so I don't have to set the levels myself), and the difference can be quite dramatic. Here's the original scan of my mother and her parents (Christmas, 1962?):


Here's the color corrected version:


Here's the original scan of my brother and me (note my anxious look -- this shows up a lot in my childhood pictures):


Here's the color corrected version:


Here's the original scan of my brother (whose own son looks *exactly* like him at this age). I love this picture -- just look at that big grin!

Here's the color corrected version:

I'm curious about why there is this colored cast, though. It could be a function of the film developing techniques at the time (movies from the 1960s and 70s have a very different color cast because of changing film techniques, for example). Or it might have been done intentionally for slides, as a way of compensating for the effects of the warm light being cast by the slide projector (which would have been yellowish). Or is it just a function of these slides being old, and that the colors have changed as they aged? If anyone knows why these slides might be off-color, I'd love to know the answer.