Funny you bring that up on two reasons...
I was born left handed and then broke my left arm at a young age. Hence forth, I became right handed through consistent use.
Also, there actually has been some studies that indicate that people really aren't left and right brained, but rather top and lower brained.
Check this out
"Top brained" is categorized by vision casting based on the "bottom brained" which gathers data based on what is received through the senses (emotions, experiences, etc). Another article I've read talks about how these top and low brained dichomoties can be put in four categories. But I cannot find that one as of now. Interesting, huh? I am probably more low brained, because I low learning new things involving code. It's easier for me to grab ideas from a pre-existing framework than come with something "completely" new in graphic design.
When challenged with a design project and I know I need to "push" the design further, I experience that horrible "blank" feeling. It's like something in my brain just says "I don't work that way!" and then gives up. But then I hear how people treat creativity like its a muscle. I am concerned I will wasting my time if I try to grow both "left and right" brain modules.
On the other hand, I guess could try getting good at both (design demands risk!), but how do you do that exactly? Draw with my left instead of my right? Talk backwards? (j/k, lol)