Twin Studies Found the Following Correlation Coefficients (R) for Monozygotic

Essay

Twin studies found the following correlation coefficients (r) for monozygotic (MZ) vs. dizygotic (DZ) twins: $\begin{array} { | l | l | l | } \hline& \mathrm { rMZ } & \mathrm { rDZ } \\\hline \text { Alcoholism (males) } & 0.4 & 0.21 \\\hline \text { Autism } & 0.65 & 0.1 \\\hline \text { Reading disability } & 0.75 & 0.45 \\\hline \text { Schizophrenia } & 0.5 & 0.19 \\\hline\end{array}$ Data from Plomin R, Owen MJ & McGuffin P (1994) Science 264:1733-1739.
Which mental trait has the lowest heritability (contribution of genetic differences to trait differences)? Briefly explain your reasoning.