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Download full textVan den Daele, Leland D. – Journal of Genetic Psychology, 1972
A classification of natal influences is proposed with a model of their operation. Natal influences affect maternal capacity, maternal load, and maternal efficiency. Since maternal load is increased in twin pregnancy, results of twin studies must be generalized with caution. The method of co-twin control is exemplified by examination of a small…
Descriptors: Bibliographies, Genetics, Heredity, Individual Characteristics
Vandenberg, Steven G.; Johnson, Ronald C. – 1966
Ronald C. Johnson argued that if early environmental stimulation or deprivation has a significant effect on intellectual ability, then individuals who are genetically identical and who are exposed to a common early environment should resemble one another more closely in IQ than similar individuals who have not shared a common environment. Johnson…
Descriptors: Comparative Analysis, Early Experience, Environmental Influences, Family Influence
