If you're like most people, you probably haven't spent a whole lot of time thinking about your thumbs. Sure, you know they're there. And maybe you've wondered if they count as a finger or not, but that's about it.
If you have a straight thumb, you might be the kind of person that people say needs to “loosen up” a little. But then again, you may also be a leader who knows when it's time to get people to stop goofing around and focus on an important task.
On the other hand, not taking things seriously has its disadvantages. You may have a tendency to not be terribly concerned with completing your work. Or all your joking around could be seen as an unwanted distraction by others.
If the bottom of your thumb is longer than the top, then you may be a good observer. You could be an introverted person who enjoys being alone with your thoughts. However, this may make it hard for others to get to know you.
How accurate these thumb personality indicators are is up for debate. But take a look at your thumbs and judge for yourself. You may find that the angle and shape of your thumb perfectly predict the type of person you are.