In natural populations, during sexual reproduction at the time of fertilization, the ratio of zygotes by sex, as a rule, is close to 1: 1 – this is the primary sex ratio. In the future, the sex ratio at the embryonic stage may vary depending on various environmental factors. In the embryonic period, the influence of environmental factors is superimposed on the genetic condition of the sex, which leads to the formation of a secondary sex ratio. By the time of puberty, the sex ratio changes and a tertiary sex ratio is formed. It depends on the resistance of individuals of different sexes to environmental factors, which is associated with physiological, environmental, behavioral and other characteristics of males and females.
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.