Fraternal twins reared together have less similar intelligence test scores than do:
A biological siblings reared together.
B adopted children reared together.
C parents and their biological children living together.
D identical twins reared apart.
The correct answer and explanation is :
The study of identical twins raised apart serves as a powerful natural experiment to disentangle the influences of genetics (nature) and environment (nurture) on human behavior and characteristics. Identical twins, or monozygotic twins, originate from a single fertilized egg that splits into two embryos, resulting in genetically identical individuals. When these twins are separated early in life and raised in different environments, researchers can observe the extent to which genetic and environmental factors contribute to various traits.
One of the most notable investigations in this field is the Minnesota Study of Twins Reared Apart, initiated in 1979. This extensive study assessed over 100 pairs of identical twins who had been separated at or shortly after birth and raised in diverse settings. The findings were striking: despite being raised in different environments, these twins exhibited remarkable similarities in numerous aspects, including intelligence, personality traits, and preferences. For instance, about 70% of the variance in IQ scores was found to be associated with genetic differences
These observations suggest that genetic factors play a significant role in shaping individual differences. However, it’s essential to acknowledge that environment also contributes to these traits. The study found that while many characteristics are influenced by genetics, the environment can modify or influence the expression of these traits. This interplay between nature and nurture highlights the complexity of human development.
In summary, research on identical twins raised apart provides compelling evidence for the substantial impact of genetic factors on human behavior and characteristics. Nonetheless, the environment remains a crucial element, interacting with genetic predispositions to shape individuals uniquely.