The age at which girls reach sexual maturity could be determined by "imprinted" genes.

The activity of imprinted genes varies depending on which parent passes them down, indicating a possible "biological conflict" between parents regarding their child's rate of development, Boston University Medical Center reported. The findings were published today in the journal Nature.

To make their findings the researchers looked at over 180,000 women of European descent. The data was collected by scientists from 166 institutions across the world. They were able to identify 123 genetic variations that were linked to the timing in which girls experienced their first menstrual cycle. Six of thee gene variants were discovered within

The activity of imprinted genes is determined by which parent they are passed down from. Some of these genes are only active when passed down from the mother while others are only active when passed down from the father. Both types of imprinted genes were found to have a say in the age of first menstrual cycle in offspring.

The team found further evidence of the imbalance between inheritance patterns by analyzing the association between imprinted genes and the timing of puberty onset in a study encompassing over 35,000 Icelandic women. This study marks the first time These women were selected because information on their family trees was available to the researchers

"Our findings demonstrate a complex network of genetic factors underlying the timing of menarche. Menarche is associated with the development of health conditions later in life in women such as diabetes, cardiovascular disease, and breast cancer. By studying genetic factors we hope to better understand how puberty timing in girls is linked to important health conditions in women," said senior author Joanne Murabito, MD, ScM, associate professor of medicine at Boston University School of Medicine /Framingham Heart Study.

The study was supported in the US by grants from the National Institute on Aging.