People's feelings toward fear may be summed up in a single gene, explaining why some people love horror movies and some people hate them, scientists now believe.

The gene affects a chemical in the brain and is linked to anxiety. People with one version of the gene are more easily startled when viewing unpleasant pictures that the ones with the other.

The first set find it harder to keep their emotions in check and may be more prone to anxiety disorders.

Known as COMT, the gene comes in two versions — Val158 and Met158 — and controls the effect of a signaling chemical in the brain linked to emotion.

Researchers measured the "startle response" of 96 women with different variations of the gene by attaching electrodes to their eye muscles.

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