Objective: To test the potential feasibility for studies conducted in twins reared apart and together from the Chinese National Twin Registry (CNTR) and to answer the question whether the rearing environment affects chronic disease risk factors.
Methods: The samples were composed of twins from two sub-registries, which included 503 twin pairs in Lishui and 505 twin pairs in Qingdao.
Results: There was a big difference in the rates of twins reared apart in different areas (from 0.6% in Qingdao to 5.4% in Lishui). Only nine pairs of dizygotic twins reared apart in Lishui were recruited. The intraclass correlation coefficients for many indices were not significant. Rearing environment might affect diastolic blood pressure and smoking behavior, but it was hard to interpret its impacts in systolic blood pressure, body mass index, waist-hip ratio and drinking behavior.
Conclusion: The design of twins reared apart is a valuable study and can be conducted in the CNTR, but the current sample size is still a big issue which requires the registry to recruit more twins to support it.