755 ILCS 5/4-10

Effect of child born after will.) Unless provision is made in the will for a child of the testator born after the will is executed or unless it appears by the will that it was the intention of the testator to disinherit the child, the child is entitled to receive the portion of the estate to which he would be entitled if the testator died intestate and all legacies shall abate proportionately therefor.