Women whose mothers have big hips may be more likely to develop breast cancer, research suggests.
Hip size is linked to levels of the hormone oestrogen
A study led by the University of Southampton found breast cancer rates were more than three times higher among women whose mothers had wide hips.
Rates were more than seven times higher if those mothers had already given birth to one or more children.
The American Journal of Human Biology study suggests high levels of the sex hormone oestrogen are to blame.
It is widely thought that oestrogen can increase the risk of breast cancer in some hormone-sensitive women, possibly by causing instability in the DNA.
And women with big hips are thought to have high levels of oestrogen.
The researchers believe that breast cancer risk may be raised for a daughter during the first weeks of pregnancy if the embryo's developing breast tissue are exposed to particularly high levels of oestrogen circulating in the mother's blood.
The researchers examined the records of more than 6,000 women born in Helsinki between 1934 and 1944. Of these 300 developed breast cancer, and 48 went on to die from the disease.
The study specifically linked a woman's chances of breast cancer to her mother's intercristal diameter - the widest distance between the wing-like structures at the top of the hip bone.
Women were at the greatest risk if their mother's intercristal distance was more than 30cm.
The risk was even higher if these wing-like structures were also round.
The researchers said their work supported the hypothesis that wide, round hips reflect high levels of sex hormone production at puberty, which continue into adult life, and impact on the embryo during pregnancy.
Lead researcher Professor David Barker said: "A woman's hips are shaped at puberty when the growth of her hip bones is controlled by sex hormones, and also influenced by the level of nutrition.
"Every woman has a unique sex hormone profile which is established at puberty and persists through her reproductive life.
"Our findings show for the first time that the growth spurt of girls at puberty is strongly associated with the risk of breast cancer in their daughters."
Dr Lesley Walker, Cancer Research UK's director of cancer information, said: "The importance of oestrogen in stimulating the growth of breast cancer is well known.
"While this study appears to show an effect that crosses a generation we would need to see the results confirmed in follow-up studies."