This is the emergence of new combinations during meiosis and fertilization, as well as the transfer of genetic material from cell to cell, for example, during conjugation of protozoa. Sexual reproduction provides significant genotypic diversity, and hence the variability of organisms. Siblings are like parents, and at the same time, each is individual, has its own unique features. This is because the parental genes were combined in all kinds of combinations twice: during meiosis and as a result of gamete radiance. It is impossible to determine which combinations appear in the offspring.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.