The report, from researchers at Oxford and the University of Exeter in England, is said to be the first evidence that a child’s sex is associated with a mother’s diet. Although sex is genetically determined by whether sperm from the father supplies an X or Y chromosome, it appears that a mother’s body can favor the successful development of a male or female embryo.
The study, published in the journal Proceedings of the Royal Society B: Biological Sciences, shows a link between higher energy intake around the time of conception and the birth of sons. The difference is not huge, but it may be enough to help explain the falling birthrate of boys in industrialized countries, including the United States and Britain.
The reason food intake may influence the development of one sex of infant rather than another isn’t fully understood. However, in vitro fertilization studies show that high levels of glucose encourage the growth of male embryos while inhibiting female embryos.
Someone in the comments wondered if this meant that diabetic mothers had more male children.