By: Mrunal Bagal
A doppelganger is the exact replica, appearance wise, of a living organism. However, do doppelgangers actually exist? There are several genetic factors that prove the fact that nobody has a doppelganger. During Meiosis, a diploid germ cell creates 4 haploid cells. However, there are several steps in the process, which are contributors to genetic variation. The 4 haploid cells are completely different from the parent cell (germ cell). During prophase 1, 2 different homologous chromosomes cross over each other. This means that parents of the chromosome (usually the arms) are switched. The gene codes for the same trait, but the way the gene/trait is expressed can be different due to crossing over. There can be many possibilities of chromosomes forming after crossing over. This is why you look like a mix of your mom and dad, but may also have your own unique traits.
Mutations are another cause for genetic variation. Right after prophase 1 comes metaphase 1. This is where the homologous chromosomes (after crossing over), line up in the middle. Independent assortment happens when the spindle fibers pull random pairs of chromosomes, forming 2 haploid cells. Consequently, there are multiple variations that can be formed. The chromosomes/DNA arises from many possible combinations of the paternal and maternal chromosomes. Another mutation, called nondisjunction, can occur in anaphase 1. This is where unequal amounts of chromosome pairs get pulled to each cell. This is a major factor in genetic variation since gametes will differ significantly.
One final factor that plays a significant role in genetic variation is epigenetics caused by environmental conditions. An epigenome is a set of chemicals that attach to DNA and proteins. These molecules can inhibit/stimulate gene expression. Environmentally-induced epigenetic changes are triggered by environmental changes, such: diet, chemicals, radiation and medication. Therefore, epigenetic changes make an organism distinct from other organisms over the course of life.
In conclusion, you can have a person look similar to you, such as your sibling. However, they won’t have 100% of your DNA, because of multiple genetic combinations/variations, mutations, and environmental factors. Therefore, unless you have an identical twin, nobody has a doppelganger. An organism develops with its own, unique DNA with small but significant variations, which makes the organism different from others.
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