1. Introduction about genetics

Molly Sinert was puzzled when the doctors informed her that she shared \(49.96\) % of Isabel’s DNA. She was so puzzled that she couldn’t figure out who Isabel was because she wasn’t a close relative or her daughter. “I’ve never gone into labour, and I don’t have any children,” she explained. But they soon remembered and realised she might be her twin sister’s daughter, whom she had never met.

Twin sisters Molly Sinert and Emily Bushnell were separated at birth in South Korea and were adopted by families in America. Isabel is the daughter of Emily Bushnell. The sisters reunited on March \(29\), \(2021\), and were happier than ever.

 

 

This real-life incident shows the link between humans across generations. Molly Sinert has a characteristic link with Isabel because she is her nephew, shown as a \(49.96\%\) similarity in their DNAs.

 

This DNA link that connects the Sinert, Bushnell and Isabel is the same link that connects us with our parents, siblings, grandparents and even with the people in our family tree who lived thousands of years ago.

 

  

Intuitively, the similarities between you and your parents or grandparents are because you obtained those characteristics from them. So, we can say that transferring characteristic traits of  parents to their offspring is similar to that of copying and transferring data from one storage device to another.

Now the question arises. How are these characteristics transferred? How inheritance of traits happened from one generation to another? Was there any substance that carried information from parents to their offspring?

After the discovery of genes by Gregor Mendel, a new field of biology opened up for research and study.

As mentioned above, characteristic features of an organism are obtained through the replication of genes from its parents. But during this replication, variations in genes will also occur, which gives the organism some distinct traits compared to its parents.

 

In the sexual reproduction of animals, including human beings, the number of successful distinct variations among individuals is high. Even in asexual reproduction, there are some amount of variations.

 

The long-term consequences of the accumulation of variations occur due to the transfer of traits for many generations. This accumulation of variations is the basis of the occurrence of evolution.