Antoine Boutros - Genetics is the process by which features are transmitted from the parent to the offspring. However, it is an uncertain process; we cannot determine its direction in advance. The child may bear his/her father’s facial features and his/her mother’s hair color. The contrary is also possible; a tendency towards mathematics may be revealed in a family that does not even know the basics of counting on the fingers of the hand. The child may also bear a congenital deformity, although his/her parents have a normal body. It is not necessary for a newborn to share the exact characteristics of the parents. The scientist Pasteur was the son of a tanner and a maid, the painter Cézanne was the son of an old banker and a farmer. Until recently, it was believed that the father would plant a miniature version of himself in the womb of the mother, and that the function of the mother would not exceed feeding the baby.

Mendel, a monk and undoubtedly the father of genetics, noted that plants with long trunks that hybridized with plants having short trunks produced a first generation of long or short plants but not plants of moderate length. He also noted that “length” is a characteristic with a stronger influence than “shortness” and that purple is stronger than white, which means that there are dominant traits that triumph over others. But when he paired the plants of the second generation, he noted that long plants could produce short plants if one of the parents was short. This also means that there are recessive traits, which means they are inherited but weak; they are not eradicated, but appear in the subsequent offspring without any change, generation after generation. These observations have shown that there are some predictable elements in genetics. If we cannot know the length of the next plant, then if we apply the principle of probability we can at least estimate the proportion of the expected long plants. In other words, this obscure monk directed genetics out of the realm of illusions and into the scope of mathematical laws. However and most importantly, the laws of genetics apply to all creatures from beans to men.

The number of traits that are passed from one generation to another by a single gene is very little. The human skin for example is affected by at least eight different genes. This explains the existence of the great diversity in skin colors. Moreover, some other qualities such as intelligence or body and facial structures are based on hundreds of genes; which is why the inheritance of these characteristics can be accompanied by a number of abnormalities. It is not surprising that primitive peoples, who were expecting their leaders to give birth to strong and clever children, were often extremely disappointed. This was not only limited to primitive peoples, indeed Spartans used to throw newborns in a ravine if they had a weak body.

In fact, the likelihood of the emergence of human beings looking exactly the same is very rare; with the exception of identical twins who emerge from a single fertilized egg. This is because there are more than 8 million combinations (23 chromosomes from the mother with 23 chromosomes belonging to the father). Thus, the possibility of having a child similar to his/her brother is approximately 1 to 70 billion. If we take the father and mother, and we assume that each one of them has only a couple of genes for each single chromosome, the combination between these genes resulting from fertilization gives 19,000,000,000,000 genetic hypothesis. Since each chromosome includes 1,250 genes, this means that the likelihood of symmetry is a number that cannot be described and is written the following way: 1 followed by 9,031 zeros.

Every species of organisms has a fixed and specific number of chromosomes. Human beings have 46, i.e. 23 pairs. It is worth noting that it is only in the 1950s that scientists verified the exact number of chromosomes in the human body. White rats have 42 chromosomes while peas have 14.  On the other hand, an animal called Rhizopod, which consists of a single cell, has more than 1,500 chromosomes.