You may have heard about dark personalities and their many problems. Well, it turns out that nice people have their own problems, and they often involve money.

Even when agreeableness was measured in childhood, it still predicted greater financial hardship later in life.

The money troubles appear to be driven by the fact that nice, easygoing types simply care less about money than other people do, according to a study that used data collected on over three million people in the United Kingdom. It found that agreeable people have a pronounced tendency to have financial problems, such as lower savings, higher debt and a higher likelihood of bankruptcy.

Previous research had suggested that agreeableness was associated with low credit scores and income. Sandra Matz of Columbia Business School and Joe Gladstone from University College London wanted to see if this also held true for other financial indicators and if it did, they wanted to dig a little deeper into the underlying causes.

People from North Devon were, on average, much more agreeable than those from Middlesbrough. They also had a 50 percent higher bankruptcy rate.

It has been suggested that the financial problems of agreeable people might stem from their having a more cooperative negotiating style — in everything from asking for a raise at work to dealing with those who owe them money. It was assumed that they make fewer demands and more concessions and end up holding the short end of the stick, monetarily speaking. However, it is just as possible that their financial problems could stem from the fact that they simply care less about money.

Using multiple methods and sources, including national survey data, bank account data and online panels, the team found that agreeableness and financial hardship did indeed tend to go hand in hand. They also found that at least part of this was due to caring less about money. Negotiating style didn't seem to play a part.

One portion of the study looked at similar districts in the UK, testing the relationship between people's agreeableness, using information collected by the BBC Big Personality Test, and the local bankruptcy rate. They found that the more agreeable an area's people were overall, the higher the area's bankruptcy rate.

For example, North Devon and Middlesbrough are two areas in England with roughly equal average incomes. People from North Devon were, on average, much more agreeable than those from Middlesbrough (2.5 standard deviations worth). They also had a 50 percent higher bankruptcy rate.

The study appears in the Journal of Personality and Social Psychology.