10/11/2013 10:00 EDT | Updated 01/23/2014 06:58 EST

Glass always half-empty? Your genes may be to blame

If you have a doom-and-gloom outlook, the news only gets worse: The root of your glass-half-empty existence could be permanently etched in your genetic makeup.

Researchers from the University of British Columbia, Cornell University and Toronto’s Centre for Addiction and Mental Health report in the journal Psychological Science that a gene variant can cause individuals to perceive the negative side of every situation.

UBC Prof. Rebecca Todd said the ADRA2b deletion variant influences not only emotional memory, which was previously known, but also amplifies a person's real-time perception of events, for better or for worse.

"Some individuals are predisposed to see the world more darkly than others," Todd said. "What we found is that a previously known genetic variation causes some individuals to perceive the world more vividly than others and, particularly, negative aspects of the world."

In the study, 200 participants with and without the gene variant were shown a series of words in rapid succession. The words were preclassified as either positive, negative or neutral.

Todd said all the participants tended to perceive the positive words better than the neutral words, but individuals with the gene variant tended to perceive the negative words better than those without the gene variant.

"We've all heard the expression 'seeing the world through rose-coloured glasses.' This is like seeing the world through gene-coloured glasses — tinted, a bit darkly.

"So you might say, 'Oh, look at that waterfall and the amazing view, and we can look over the edge of this cliff here...' and somebody who is a deletion variant carrier may look at the same scene and see dangerous rocks that might fall, or places snakes may lurk, or bears," Todd said.

Todd said other factors such as cultural differences or life experiences also influence individual differences in emotional perception, and that she has begun exploring the gene variant's effects on those with post-traumatic stress disorder.

Further research is also planned to explore the gene variant's occurrence across different ethnic groups.

While it is believed more than half of Caucasians have ADRA2b, some studies suggest it is much less prominent in other ethnicities, she said.