First, there was evidence of effect sizes that fell substantially outside of the expected funnel distribution for heritability, environmentality, and corrected environmentality. For heritability, the distribution of residual effect sizes was negatively skewed with a few highly negative values (for environmentality, the distribution of effect sizes was positively skewed). These effect sizes were primarily drawn from the first years of life. Returning to Figure 3, it is apparent that there are several effect sizes that indicate low heritability during this period of the lifespan. However, all of these studies are very low precision, and the estimated trend line reflects several high precision, high heritability estimates. There are a few possible explanations. If heritability approaches the upper limit of 1.0 near birth then it is not logically possible for deviations to occur such that heritability accounts for more than 100% of the variance. Rather, the small sample and low precision studies will be more likely to estimate heritability to be lower than the high precision studies due to the greater amount of sampling variability. Alternatively, it may be the case that
