All signs point to yes. During the past several months, the image has flickered into our homes with increasing regularity: Following the end of a campaign-trail speech, little Emma Claire Edwards, 6, and Jack Edwards, 4—both blond and cherubic—joyfully run up to the stage where their dad, Sen. John Edwards, 51, scoops them into his arms. Standing nearby beaming, always, is Elizabeth Edwards, 55. Do the math, and it's not hard to figure out that Edwards gave birth to Emma Claire at age 48 and Jack at 50. And yet if Edwards used her own eggs, this is all but...