Which thumb is on top?

I did a little test (to analyse the brain) yesterday, and one of the questions was to see which thumb is on top when you clasp your hands. I never thought of it, but I just realised that I will always clasp my hands the same way, and if I change it, it just feels weird... Try it and see! This is the scientific explanation that they gave me:

You said your left thumb is on top. This suggests the right side of your brain is dominant.
The left side of your brain is said to be more adept at language, logic and linear thinking.
The right side of your brain is said to control your visual, spatial and intuitive processes.

It's a little weird though...since I'm right-handed I would have thought that my left brain would be dominant...

How about you?