A team of British and Israeli researchers has carried out a study and found that a woman's muscle mass may have less to do with exercise and avoiding sweets than it does with the DNA of her parents.

"We have known that obesity is heritable – but this study shows the importance of genes determining how much muscle each of us has -- which determines body shape and also athletic abilities. Finding the genes responsible will have major impacts on sports as well as explaining why many people will never obtain the perfect figure," lead researcher Prof Tim Spector was quoted by The Daily Telegraph as saying.

In their study of 3,000 middle-aged British women, Prof Spector from King's College in London and Prof Gregory Livshits from Tel Aviv University focused on brawn, sinew and shape more than obesity.

The team measured the volunteers' ‘total lean mass’, one of the three major components of total body weight along with bone, and compared it to markers in their genes.

When controlling for age, and fat, the researchers found that genes account for over half of the differences in womens' body sizes -- the study has been published in the Journal of Clinical Endocrinology and Metabolism.