I'm a left thumber on top. I guess it's a reflex, because I'm also somewhat ambidextrous, both on the hands and legs. My dominant hand is my right hand, but when needed I can use my left hand. When I ice skate, the left leg is dominant and I speed skate and spin on my left leg. When playing soccer, my right leg is dominant.

Right thumb up. I have no trouble doing it the other way, but I have to think left up before I do it.

My left thumb automatically went on top; I'm right-handed, but it felt very awkward to put the right thumb over the left one. But sometimes I still wouldn't know my right from my left, if I hadn't been vaccinated on my left arm--many, many, many years, ago! :>)

I had my right-handed small son put out his hand as if I was going to shake it. He extended his right hand and didn't forget which was his right. But with my left-handed little daughter, I handed her a crayon and she took it with her left hand. She felt special because she was the only left-hander in the family.

When I first visited her school, I asked the principal how the school handled left handed students. She said that they made the children shift hands so they would learn to do things correctly. She wasn't there long after this, not that I had anything to do with it. She just believed in doing everything the old-fashioned way. How it must have confused the children when they would not be allowed to do things the way nature intended.

I am naturally right-handed but that hand was in a cast and bandaged for a long time from two surgeries when I was almost four.

Having to use my left hand so much at that age has made me somewhat ambidextrous.

In clasping my fingers, the left thumb went on top. Is this normal for right-handers?

I'm left-handed, and my right thumb ended up on top. Interesting thread!