ObjectiveTo determine the extent to which the correlation of systolic blood pressure, diastolic blood pressure, body mass, fasting total cholesterol and fasting triglycerides in young adulthood reflects common genetic or environmental influences.DesignCardiovascular risk factors were measured in a community sample of 129 monozygotic and 67 dizygotic twin pairs, ages 18–30 years.MethodsMultivariate twin structural equation modelling allows estimation of the extent to which the covariation of two or more variables is attributable to common genetic and environmental factors and was used to analyse the correlation among systolic blood pressure, diastolic blood pressure, body mass index, fasting total cholesterol and triglycerides.ResultsThe covariation of risk factors was partially attributable to a single common genetic factor, while the covariation of systolic blood pressure, body mass index and triglycerides was also, in part, attributable to a common non-shared environmental factor.ConclusionsGenetic and, to a lesser extent, non-shared environmental factors contribute to the covariation of cardiovascular risk factors in young adult twins. Nonetheless, it should be noted that these common influences account for a relatively small percentage of the variance in each risk factor compared to genetic and environmental factors that are risk factor-specific.