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Intellectual development of twins -- comparison with singletons
Acta Geneticae Medicae Et Gemellologiae
|January 1, 1976
Summary
Twins consistently show lower scores on cognitive and motor tests compared to singletons. These performance gaps are more pronounced in Black children and linked to prenatal factors and congenital issues, though some effects may lessen with age.
Area of Science:
- Pediatrics
- Developmental Psychology
- Genetics
Background:
- Twin studies are crucial for understanding genetic and environmental influences on development.
- Previous research indicates potential developmental disparities between twins and singletons.
Purpose of the Study:
- To analyze cognitive and motor test performance differences between twins and singletons.
- To investigate the contributing factors to observed performance gaps in twins.
Main Methods:
- Analysis of mental, motor, and intelligence test scores from the Collaborative Perinatal Project.
- Comparison of performance between twins and singletons, stratified by race.
- Assessment of twins raised as singletons to differentiate environmental influences.
Main Results:
- Twins demonstrated poorer performance on mental, motor, and intelligence tests compared to singletons.
- Performance disparities were greater among Black twins compared to White twins.
- Twins raised as singletons performed at the level of twins, not singletons, indicating prenatal environmental impact.
- Higher incidence of congenital malformations in twins, particularly central nervous system issues, contributed to poorer outcomes.
- The performance gap between twins and singletons narrowed between ages 4 and 7, suggesting prematurity's effects may be reversible.
Conclusions:
- The lower performance of twins is multifactorial, influenced by prenatal environment, congenital malformations, and prematurity.
- Prenatal factors significantly impact twin development, independent of postnatal upbringing.
- Prematurity's negative effects on twin development may be mitigated over time.
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