Panels (A–C) are for the high-risk exclusion (HRE) strategy, while panels (D–F) are for the lowest-risk prioritization (LRP) strategy. The details are as in Figure 2, except the following. First, we fixed the prevalence to and the heritability to (note that the heritability was not needed in previous figures). Second, in the simulations, we first drew the parental genetic components: and for the mother, and and for the father, where are the polygenic scores and represent non-score genetic factors (Appendix Section 6). We drew the environmental component for each parent as and computed the liability of each parent as . If the liability of a parent exceeded (the upper -quantile of the standard normal distribution), we designated that parent as affected. We then stratified the risk reduction results based on the number of affected parents: 0 (panels (A) and (D)), 1 (panels (B) and (E)), and 2 (panels (C) and (F)). Note that as expected, the number of families in which both parents are affected is small, and thus, the results in panels (C) and (F) are noisy. For each set of parents, we drew the PRS of each embryo as (), where is an embryo-specific component of the score (independent across embryos). We then selected one embryo from each family based on either selection strategy. We computed the liability of the selected embryo as , where is the embryo-specific component of the non-score genetic factors, and is the environmental component of the embryo (Appendix Section 6). The embryo was designated as affected or unaffected as described for the parents. We computed the risk reduction (according to either strategy) relative to a baseline, obtained from the same sets of simulations when we always selected the first embryo. The baseline risk is indicated on top of each panel. We computed the theoretical relative risk reduction for the two strategies as summarized in Appendix Section 6.9.