 For example, a study of children born to twin sisters investigated whether the relationship between parental divorce and offspring alcohol and emotional problems was causal or confounded by parental genotype.The study found that the offspring of twin sisters who were discordant for divorce had equally high levels of emotional problems, suggesting that genetic factors which made twin siblings divorce-prone also increased their children’s risk for depression and anxiety.This finding suggests that preventing the parents’ divorce would have had little impact on offspring risk for emotional problems (although the findings for alcohol problems in the children were consistent with a causal role for divorce).