Genetic variation can be described as the variation in the genotype of organisms. Genetic variations are usually caused due to the meiosis. During meiosis, crossing over and homologous recombination occurs which allows genetic variations to occur. Due to this, about 50% of the DNA is different among siblings. 50% of the DNA is different in the parents and the offsprings. Hence, we can say that siblings are 50% genetically identical.
fun fact : What is the difference between a bacterial cell and an animal cell?
Nucleus: The most important difference between a bacterial cell and animal cell is that the bacterial cell does not have a membrane-enclosed nucleus. Instead, the bacterial cells keep its genetic material in an irregularly spaced region called nucleoid.