Contributions of genetic and environmental factors

When studying twins to ascertain the contributions of genetic and environmental factors to disease development, which of the following statements is not true? Select one: in dizygotic twins, both environmental and genetic factors could cause disease monozygotic twins also share much of the same environment in monozygotic twins concordant for a disease, then the disease could only be genetic monozygotic twins share of their genetic material if both twins do not have the disease, they are concordant for the disease When designing randomised clinical trial, issues to consider around the data collection or subjects include the following, except Select one: outcomes of treatment prognostic profile at entry external validity assigned treatment masking