Abstract
Prior research has reported convergence of monozygotic (MZ) cotwins' intelligence scores over time, with divergence observed between dizygotic (DZ) cotwins. These patterns have been variously explained with reference to the increased influence of genetic factors (MZ and DZ twins) and nonshared environmental factors (DZ twins), and the reduced effects of shared environmental events (DZ twins). Studies of unrelated siblings have found modest within-pair resemblance in intelligence, with increasing divergence over time. This subject is revisited in a study using three novel kinships: young reared-apart MZ twins from China (CTA-MZ), adult reared-apart twins from Denmark (D-MZA) and findings from a previous study of same-age unrelated siblings (virtual twins or VTs). Despite modest sample sizes, the anticipated trends described above were observed, replicating extant findings. Intraclass correlations for overall IQ score at Time 1 and Time 2, respectively, were ris = 0.51, 0.81 (CTA-MZs) and ris = 0.64, 0.74 (D-MZAs). The hypothesis that VTs would show score divergence at Time 2 was confirmed. Increased genetic influence (CTA-MZ, D-MZA and VT), reduced impact of shared environments (VT), and increased effects of nonshared environments (VT) appear to best explain the findings. These results also inform parent and educator expectations regarding twins' and siblings' academic performance.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
