A mother was in a nursing home and asked her attorney to draft a deed that would give her farm to her son. The attorney drew up the deed, had the mother properly execute it, and thereafter properly recorded the deed. The attorney then told the son what she had done. The son immediately went to the nursing home and told the mother that he did not want the farm so she should take back the deed. A week later, the mother returned home to the farm. Shortly thereafter, the son died without a will, leaving his wife as his only heir. The mother has brought an action against the wife to quiet her title to the farm. If the mother is successful in this action, what is the likely reason