Adoption of children is an ever-present complication of class gifts and the Rule Against Perpetuities. Given this fac any effort to find the presumption of lifetime fertility rebuttable is largely illusory. The author demonstrates that the gift in In Re Lattouf's Will could have been sustained even in face of an irrebuttable presumption.
Waggoner, Lawrence W. "In Re Lattouf's Will and the Presumption of Lifetime Fertility in Perpetuity Law." San Diego L. Rev. 20 (1983): 763-78.