The article is published in Everyman's Science magazine by Indian Science Congress Association (Aug-Sept 2018 issue) http://sciencecongress.nic.in/pdf/e-book/august_sept18.pdf
Genetic engineering is a very useful technique as per the agricultural or animal breeding aspects. We can modify the genes of an organism to improve or change its properties. This modification sometime undesirably spreads into the neighboring species via pollination or cross breeding which might either improve or deteriorate the properties of the organism. This unwanted deterioration of natural organisms due to genetically tailored one’s cause genetic pollution. Genetically modified species have been extensively synthesized over recent years increasing the risk of genetic pollution more than ever. It is well agreed and proven that this technique has helped in the development of many organisms with desired qualities but the ill-effects are more hazardous than those.
Many countries in the world are routing towards the righteous use of this technique as it may have devastating effects on the present organism diversity. Genetic modification may be considered as a milestone in technology but it is gradually heading towards the deterioration of the natural breeds of plants and animals.
Keywords : Genetic modification, plant diversity, transgenes.
Genetic pollution is the contamination of unaltered or natural organisms with modified genes from the genetically hybridized organisms. According to environmentalists  and various groups, genetic pollution is an undesirable phenomenon. Earlier it was described as the gene flow from domestic, non-native sub species to wild native population but lately it has been termed as the flow of genes from genetically engineered species to non-GE species. There are many terms given to this change like genetic deterioration, genetic aggression, genetic mixing, but none has been collectively agreed upon. Hence, the definition of genetic pollution remains a dispute as far as now.
The first genetically modified plant was an antibiotic tobacco plant which was introduced as the first GMO in 1983. The history of genetic pollution goes back to 1854 when an Austrian monk, Gregor Mendel discovered the Theory of Inheritance through experiments involving breeding of pea plant. Mendel was able to explain the very basic form of inheritance and assumed that some heritable material is present in the pea plant which is able to transmit its traits to the offspring plant. About a century later, in 1962, Francis Crick and James Watson  won the Nobel Prize in Medicine for deciphering the structure of DNA which is till date the basis of inheritance.
2. Genetic modification
The DNA molecule consists of two chains that twist around each other forming an anti-parallel double helix structure. The discovery of DNA was due to the idea of its sequence which carries all the genetic information of any organism. Some nitrogenous bases called pyrimidines and purines are arranged in a specific manner in the DNA molecule itself in order to create a code which is transferred into a protein in the cell as a part of the creed of central biology. DNA is the basic unit of inheritance among the other larger units. One of those large units is gene which has the code for some product protein.
The main idea behind Genetic Modification is to find such genes within an organism which can be modified and then transmitted into target organism to finally get the desired characteristic bearing species. It can be seen as an argument with the fundamental facts of nature which has its ill effects at very microscopic level summing up to genetically derived pollution.
Genetic engineering has made us possible to modify plants and other organisms[3,4].In order to acquire desirable properties, new genes from any other species can be inserted into the subject species. These inserted genes are known as Transgenes .In few cases, the gene of the subject specie is taken out in order to compare the nature and properties of the organism. Various changes are made genetically to study the changes in behavior and characteristics. This change that takes place due to genetic modification has been termed as “undesirable” by organizations such as Greenpeace  and TRAFFIC .
Table 1: Genetically engineered crops in this table include the crops that have insect-resistant traits or crops that have herbicide tolerance traits, or both. 
3. Genetic pollution in plants and animals
Gene flow can take place undesirably from genetically tailored organism to non-genetically modified one. This flow of genes may occur via cross pollination, water pollination or animal pollination. Seeds of the genetically modified organism may reach the non-modified organisms through animals, water or cross-pollination. Genetic pollution can also occur through the mating of wild and modified organisms, producing hybrids. This undesired mixing might cause genetic pollution by interfering with the genetics of the other organisms.
The process of gene flow for animals is about same as plants although it is not very common as the genetic pollution in plants. The gene flow from one animal to other can cause genetic pollution by altering certain properties of the animal. Genetic pollution in animals is a very serious issue as it can pose harmful effect on that particular breed of organisms and sometimes can make them extinct.