Absolutely it can be learned. Some people have more of a knack for it but that doesn't mean anybody can't learn. There are many tutorials online that are aimed at beginners through professionals, no matter your level. It's never too late to start and I highly doubt anybody would regret learning. It's a great past time and skill to have that spills over into so many areas of life.
I have spoken to a couple of people about this and most of them told me that it's more like a talent rather than something that can be learned. But I guess I will have to try it myself and see. Thanks for the tips, @Mirage
It can be learned. I earned a degree in Fine Art and have taken a lot of classes in different media and the most important thing is to teach yourself to SEE things.. don't assume things are the way you think they are (Trees are not shaped like lollipops) but take time to really LOOK. My drawing professor told us to staple a sketchbook to our hand and draw EVERYTHING we saw. Did you know that shadows can be blue, not gray or black?