The newly formed dna has a new set of genes which means a new set if proteins from 2 different parents, therefore it is not identical

Introduction:
When new DNA copies are formed during cellular replication, they are not always identical due to several reasons. This phenomenon is known as genetic variation. Genetic variation is essential for the survival and evolution of species, as it contributes to diversity and adaptation to changing environments.

1. DNA Replication:
DNA replication is the process by which a cell makes an identical copy of its DNA before cell division. During replication, the double-stranded DNA unwinds and separates into two strands, each serving as a template for the synthesis of a new complementary strand. However, despite the fidelity of DNA replication, errors can occur, leading to genetic variation.

2. DNA Polymerase Errors:
DNA polymerase is the enzyme responsible for adding nucleotides to the growing DNA strand. Although DNA polymerase has proofreading mechanisms to ensure accuracy, it is not entirely error-free. Occasionally, DNA polymerase may make mistakes during nucleotide incorporation, leading to base substitutions, insertions, or deletions in the newly synthesized DNA strand.

3. Mutations:
Mutations are changes in the DNA sequence that can occur during replication. They can be spontaneous or induced by external factors such as mutagens (chemicals or radiation). Mutations can alter the genetic information carried by DNA and can result in genetic variation. These variations can be beneficial, harmful, or neutral depending on their impact on the organism.

4. Recombination:
Recombination is another source of genetic variation. It occurs during meiosis, the process of cell division that produces gametes (sperm and eggs). During meiosis, homologous chromosomes exchange genetic material through a process called crossing-over. This exchange of genetic material leads to the shuffling and mixing of genetic information, resulting in new combinations of alleles in the offspring.

5. Epigenetic Modifications:
Epigenetic modifications are chemical changes to the DNA and associated proteins that can affect gene expression without altering the DNA sequence itself. These modifications can occur during DNA replication and can result in heritable changes in gene activity. Epigenetic modifications can contribute to genetic variation by influencing gene regulation and expression patterns.

Conclusion:
In conclusion, newly formed DNA copies may not be identical due to various factors such as DNA polymerase errors, mutations, recombination, and epigenetic modifications. These sources of genetic variation are crucial for the survival and adaptation of organisms, as they provide the raw material for evolution and diversity in populations. Understanding the mechanisms of genetic variation is essential in fields such as genetics, evolutionary biology, and medicine.