Are you an eternal pessimist?

Do you always look on the bright side or life or does a dark cloud perpetually follow you around? According to new research, it's down to our DNA.

Scientists have found that people who have inherited two copies of the gene which controls the feel-good chemical serotonin are likely to have an optimistic outlook on life.

Take this fun test to see if you are the type to see a glass as half empty or half full!