Genetics may cause some women to develop eating disorders, as new research suggests the psychological power of beauty and self-image varies from person to person.
Researchers at Michigan State University have found some women experience greater innate psychological pressure to be thin than others, a phenomenon they have named thin-ideal internalisation.
Jessica Suisman, lead author on the study, said: "We're all bombarded daily with messages extoling the virtues of being thin, yet intriguingly only some women develop what we term thin-ideal internalisation. This suggests that genetic factors may make some women more susceptible to this pressure than others."
Around 1.6 million people in the UK are affected by an eating disorder. It is estimated that 20 per cent of anorexia sufferers will die prematurely because of their illness, while bulimia is associated with severe medical complications.
In order to determine whether genetic factors come into play, the researchers studied over 300 female twins between the ages of 12 and 22. They looked at the differences between identical twins, who share 100 per cent of their genes, and non-identical twins, who share just half.
Participants were asked how much they wanted to look like famous people, after which their levels of thin idealisation were determined.
Findings showed that identical twins have closer levels of thin idealisation than non-identical twins. Heritability of thin idealisation was found to be 43 per cent, which suggests genetics can explain why women differ in how they perceive thinness in almost half of all cases.
Environment was also found to play a role, with differences between twins' environments having an impact on thin internalisation. Non-shared environmental factors, such as friendship groups and participation in weight-focused sports such as dance, were found to increase levels of thin idealisation.
Commenting on the study, Leanne Thorndyke, head of communications for eating disorder charity b-eat, told IB Times UK: "The causes of eating disorders are complex and not yet fully determined but include genetic, psychological, environmental, social and biological influences. Poor body image and low self-esteem are key factors in the development of eating disorders and social and cultural pressures are strong in this area.
"Body image is a key part of our sense of identity and not a trivial matter or one of personal vanity. It is a fundamental part of our sense of self and affects our thoughts, emotions and behaviour.
"What the latest research is telling us is that an eating disorder is much more hard wired and biologically based than was previously thought to be the case. A number of risk factors need to combine to increase the likelihood that any one individual develops an eating disorder.
"Eating disorders can be beaten - and our understanding of the role that body image plays in this is crucial. We may not be able to change the way brains are hard wired, but we can challenge the cultural ideals that have become toxic to a generation."