1. Right thumb on top
If your right thumb is on top, it shows that you are a person who prioritizes logic. You're used to making decisions based on facts. If something seems irrational, you won't like it.
Beyond that, you are a very creative person. You love exploring new ideas.
If your two thumbs are in a parallel position, then you are a person who is very careful in making decisions. You will pay attention to various things so that all decisions made can be fair and balanced.
On the other hand, you are known to be friendly and able to make people around you feel comfortable.
If your left thumb is on top when you stick your hand out, it shows that you care deeply about the people around you. You have a high sense of empathy, and are the first to realize when a friend is sad.
Because of your high empathy, you are well-liked by your friends. People will feel comfortable with everything you do, because you are very reliable.