The difference in height between people is mainly due to the environment - not genetics

This is according to a study conducted by researchers at the Technion, Tel Aviv University and Bnei Zion Hospital in Haifa

When is a person's final height determined? The answer is surprising: it is mostly determined before the age of one year! This surprising fact emerges from an article published in the Journal of Pediatrics. In the pioneering study, in which 162 pairs of twins participated, it was found that the most important element in determining a person's future height is the environment in which he lives in the first year of his life. The study was conducted at the Technion, Tel Aviv University and Bnei Zion Hospital, in collaboration with the health bureaus in Haifa and Tel Aviv.

The researchers' conclusion, according to this study and previous studies led by Professor Zeev Hochberg of the Rappaport Faculty of Medicine at the Technion, is that a person's final height is determined to a large extent (50%) by the conditions of growth in the womb and in the first year of life. Although genetics have a substantial effect on a person's height, the influence of the environment is enormous. When an environment includes the following factors: the course of pregnancy, the diet and the state of health in the first year of life, the parents and the family structure, the economic and emotional situation.

"Following the genetics revolution, it is now customary to attribute a lot of weight to our genes in determining our traits," explains Professor Hochberg. "Indeed, there is no doubt that many of our traits are innate or genetic. However, as can be seen in our research, environmental conditions play a very significant role in determining these traits."

In the research of Professor Hochberg and his colleagues, the relative weight of the various factors that determine the variation in the height of an adult person was examined. The range of difference that exists between tall and short people is about 24 cm, and in the current study it was found that half of this difference is due to congenital genetic factors, and half - to environmental conditions. The researchers focused on the crucial stage, which is the stage of transition from growing a baby to growing a child (age 10.5 months, on average in Israel). They followed this transition phase and its consequences among 162 pairs of twins - 56 pairs of identical twins (that is, with the same genes), 106 pairs of non-identical twins (with different genes), and 106 pairs of non-twin siblings.

"Twin studies make it possible to examine the 'balance of power' between genetics and environment," explains Professor Hochberg. "And here we discovered the enormous power of the environment in shaping man. This is actually the 'plasticity' of development, which means that environmental conditions such as nutrition, weather and social and family situation affect our physical features. From the evolutionary point of view, plasticity 'settles' us features that will help us in our future living conditions, and it 'predicts' these future conditions based on the present conditions. Hence, children born and raised in an environment characterized by hunger will be shorter, so that they will need less food in the future. A rich and satiated environment, on the other hand, will 'grow' tall children."

Professor Hochberg's partners in the study are Dr. Alina German from Bnei Zion Hospital and Klalit Hospital; Professor Zvi Liebshitz, Dr. Ida Malkin and Dr. Inga Peter from Tel Aviv University; Dr. Yonatan Dubnov and Dr. Hana Akons from the Health Bureau in Haifa, and Dr. Michael Shmoish from the Loki Center at the Technion.