Researchers have determined that individuals who are commonly called "sensitive" have heightened activity in the empathy-related portions of their brains, and this activity level might be genetically determined.

Experts at Stony Brook University recently developed the theory that about 20 percent of the world's population is genetically predisposed to increased empathetic behavior and thoughts.

To back this claim, they launched a study examining the brains of 18 married individuals using functional magnetic resonance imaging (fMRI). Some of these people were first identified as people with high levels of sensory processing sensitivity (SPS) while others had low SPS - paying less attention to subtle stimuli and approaching situations more quickly and without as much emotion.

The results of this study are published in the journal Brain and Behavior.

According to the study, these 18 participants were shown photographs of the smiling or sad faces of various people - some of whom they knew and some of whom were complete strangers - for 12 seconds each.

Even just off the bat, the researchers noticed a markedly higher blood flow in the parts of the brain involved with empathy and emotion in "hyper sensitive people" (HSPs), compared to the other participants, regardless of who's picture was being shown to them.

"This is physical evidence within the brain that highly sensitive individuals respond especially strongly to social situations that trigger emotions, in this case of faces being happy or sad," researcher Arthur Aron said in a statement.

Interestingly, while both groups - HSPs and non-HSPs - showed increased blood flow when viewing pictures of their loved ones, the HSPs again showed the highest activity of all - tying their "sensitive feelings" in with a high SPS. Sensory processing sensitivity in-turn is associated with a number of genetic traits - indicating that being a HSP's behavior may be at-least in-part influenced by genetics.

The study was published in Brain and Behavior on June 23.