Something else to feel guilty about: eating too much fat during pregnancy may affect not only that child, but also any future granddaughter's risk of getting breast cancer.
To be clear, this study was done on rats, not people. The researchers from Georgetown Lombardi Comprehensive Cancer Center fed the pregnant first generation rats a diet that, although not higher in total calories, was 43% fat. The next two generations were fed a normal diet. Regardless of whether the second generation was male or female, the females in the third generation (granddaughters) were more likely to develop breast cancer than if their grandmothers had eaten a normal diet.
The scientists hypothesize that the increased risk is a result of epigenetic changes brought about by the change in diet. Epigenetic changes include anything other than changes in the actual DNA sequence itself, such as alterations in DNA methylation or histone binding patterns. In other words, the high fat diet is changing some aspect of the DNA that is passed on to at least two subsequent generations.