Do you ever wonder why some people are taller than others? Of course, they might have had tall parents, but now this common believe is a scientific fact. Until now there were studies that concluded that unlike obesity, which is caused by a mix of genetic and environmental factors, 90% of normal variation in human height is due to genetic factors. But those studies failed to prove if there is specific gene responsible for height.

But a new research lead by Dr Tim Frayling from the Peninsula Medical School, Exeter, Professor Mark McCarthy from the University of Oxford and Dr Joel Hirschhorn from the Broad Institute of Harvard and MIT in Cambridge have identified the first gene, known as HMGA2, a common variant of which directly influences height.

The researchers used the data from the Wellcome Trust Case Control Consortium and the Diabetes Genetics Initiative and they conducted a genome-wide study of DNA samples from 5,000 people. The findings are published online today in the journal Nature Genetics.

But in order to understand in which way a gene might make people taller than others, let’s take a look at some genetics mechanisms.

Each of us carries two copies of each gene, one from our mother and one from our father, but each copy can be a variant, or "allele". In the case of the HMGA2 gene there are two versions: one “tall” and one “short”.  

According to the study’s findings, the 25% of white Europeans carried two "tall" versions of this particular gene, making them approximately 1cm taller than the 25% of people who carry two "short" versions.

"Height is a typical 'polygenic trait' – in other words, many genes contribute towards making us taller or shorter," explains Dr Frayling. "Clearly, our results do not explain why one person will be 6'5" and another only 4'10". This is just the first of many that will be found – possibly as many as several hundred.", he added.

By discovering the gene which is responsible for height the scientists may expand their research in order to demonstrate in which way HMGA2 is implicated in growth. For the moment they believe that HMGA2 is increasing the cell production and it their hypothesis proves to be true than there might be some explanation for the development of cancer. The cancer is nothing just a unregulated cell growth and the previous studies have shown an association between height and certain cancers. Taller people are statistically more likely to be at risk from cancers, including those found in the prostate, bladder and lung.

"There appears to be a definite correlation between height and some diseases. For example, there are associations between shortness and slightly increased risks of conditions such as heart disease. Similarly, tall people are more at risk from certain cancers and possibly osteoporosis," said Dr Mike Weedon, lead author on the study.

Also those findings might help the scientists to understand how common variations in DNA in the human the genome actually affect us, especially in relation to growth and development.

"Even though improved nutrition means that each generation is getting successively taller, variation in height within a population is almost entirely influenced by our genes," says Dr Frayling. "This fact, coupled with the ease of measuring height, means that height can act as a model trait, allowing us to explore in detail the influence that the genome actually has on our general make-up, not just disease risk."