The parameter estimates and standard errors from our best-fit model in the FF twin pairs are seen in Fig. 2, and the sources of genetic influences on our 4 AC measures are seen in Table 3. We will focus here solely on results for the genetic factors. The heritability of AD in this model is estimated at 58%. Most interestingly, all of these genetic effects result from factor A1—the common factor influencing both AD and AC—and there is no evidence of specific genetic effects on AD. Thus, our model fitting suggests that in females, genetic risk for AD is entirely shared with the genetic risk factors for AC.
