A new study sheds light on the causes of early sexual development among children

Researchers from Ben-Gurion University found that the date of sexual maturation is determined according to the child's height difference compared to his parents and is intended to help him reach the 'target height'

The reasons why some children mature sexually early or late compared to the rest of their age without any pathological reason, are still an unsolved puzzle among the community of doctors and researchers. The prevailing assumption today is that the date of puberty is a genetic trait. However, genetic studies that tried to locate the genes that determine the date of sexual puberty were able, only in a very small percentage of cases, to show a connection between genetic variation and variation in the dates of sexual puberty.

A new study, recently conducted at Ben-Gurion University of the Negev and published in the journal PLOS ONE, sheds light on the reasons why the date of sexual maturation differs from child to child. In the article, researchers Dr. Yehuda Limoni and Prof. Michael Friger from the Faculty of Health Sciences, together with Słomir Koziel from the Polish Academy of Sciences in Wrocław, claim that the date of sexual puberty is determined according to the "HEIGHT GAP", which is the difference in the height percentiles of the child compared to his parents.

In a previous work, the researchers found that the date of puberty affects the final height. The hypothesis of the present study was that the effect of the time of puberty on the final height helps the children to reach the target height (the height at the end of growth), which is a weighted average of the height of the parents.

"The significance of the findings is that the date of the child's sexual maturation is not predetermined genetically, but adapts itself to the way the child grows," explains Dr. Limoni. "When the child grows on a higher percentile than his parents (the target percentile), his sexual maturation will be earlier than his peers and vice versa, when the child grows on a height percentile lower than his parents' height percentile, his sexual maturation will be later than usual. In both cases, the advance and the delay in the date of sexual maturation will help the child to finish growing closer to the target height."

For example, in the case of a tall girl whose parents are short, the date of puberty will be one that will stop the growth earlier than usual. In this way, the final height will be lower than it could have been if the girl continued to be taller at the same height percentile until the end of growth. In a pictorial way you can describe a girl who is the tallest in the class but stops growing in height at the age of the bat mitzvah when she then reaches the "goal height".

The researchers hypothesized that there is a correlation between the "height gap" and the date of puberty. In the study, the hypothesis was tested on two groups of children: Polish children who were measured consistently from the age of 8 to 18 in schools in the city of Wroclaw between the years 1961-1972 (173 boys, 162 girls) and a group of Israeli children (110 boys, 60 girls), who were referred for expert counseling between the years 2004 -2015 because of short stature or suspicion of premature puberty, but they were found healthy and without any pathological findings.

"The study confirmed our hypothesis: there is a correlation between the height gap and the date of sexual maturation," says Dr. Limoni, "the correlation is greater if you take into account the degree of obesity of the child as expressed by his BMI percentile. Studies have shown that obesity causes the advance of sexual maturation, so we also tested its effect."

The result of the research is a mathematical model that explains the dependence between the height gap and the degree of obesity of the child and the date of his sexual maturation.

"Another conclusion from the model is that each child has a suitable puberty date, which is a result of the height difference between him and his parents," adds Dr. Limoni. "A child whose sexual maturation is early compared to his peers but conforms to the model, is a child whose sexual maturation is normal even though it is early. The determination of whether sexual maturation is normal in terms of the date should not be determined according to the norm in the population, but rather personalized for the child with the help of the model. We believe that the use of this model or similar models adapted to the population of origin of the children, will reduce the use of unnecessary diagnostic procedures and provide an explanation for early or late sexual maturation that so far had no explanations."

for the scientific article