Why does careful observation of the manifestation of traits in a series of generations help to detect and study the manifestation of the laws of heredity and variability?
Within a species, all organisms are not alike; there is individual variability between organisms. The study of the causes and forms of variability is done by genetics. They do not deal directly with genes, but with the results of their manifestation – signs and properties. For generations, it is convenient to track the patterns of heredity and variability.
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.