Researchers in Southwest University in Chongqin in China studied about 250 college-aged students and identified significant differences in the brain regions associated with imagination, agreeableness and emotional regulation.
According to the researchers, the brain structure of only children reinforces "undesirable personality traits, such as dependency, selfishness and social ineptitude."
The "socialising effects" of having siblings, bestows upon most people "the realisation that they are not the centre of the world," the researchers said in the study published in the journal Brain Imaging and Behaviour.
"Only children might have more opportunities for independent activity, and independence is strongly related to creative thinking," they said.
The findings may suggest that family environment plays an important role in the development of individuals behaviour and brain structure.