While the study, which appears in the March/April issue of the journal Child Development, shows a correlation between mothers with mood disorders and their daughters' earlier puberty, Bruce J. Ellis, PhD, one of the researchers, says that a direct cause and effect relationship cannot be shown.
"Both marital and family dysfunction and early pubertal timing in daughters may be caused by common underlying genetic factors," he tells WebMD. Ellis is a lecturer in psychology at the University of Canterbury in New Zealand.
The study only looked at maternal depression, family conflict, divorce and remarriage, and when puberty began. Other factors that are known to cause early puberty, such as genetics and nutrition, were not looked at.
Puberty is starting younger and younger with each generation, according to Hadine Joffe, MD, who is director of the Women's Center for Behavior Endocrinology at McLean Hospital at Harvard Medical School. Joffe, who reviewed the study for WebMD, says the findings are an interesting evolutionary hypothesis.
The nature or nurture issue came up in the study when the authors noticed the correlation between the age of the daughter when the father left the household, and the exposure to either a stepfather or the mother's boyfriend. The researchers theorized that the influence of unrelated males on puberty could be due to pheromones. Pheromones are hormones that are thought to stimulate, through smell, sexual reactions in animals.
The pheromone theory goes along with a lot of recent interest in the sense of smell and its influence on behavior, says Arnold Licht, MD. Of course, he says, one has to be careful not to make broad associations that could have wide-range implications. More research needs to be done on the senses before this conclusion is reached, he says.