It may be destructive or creative or even both. It's interesting to note that people who tend to be religious fanatics tend to have a simian line.
Medicine has also found that simian lines may also be associated with certain types of heart defects. People with a simian line never really find peace. They spend their entire lives searching for an answer they never really find.
To the person with the simian line there is only right or wrong and nothing in between. People with this line work twice as hard, study twice as hard and fight twice as hard.