The virgin birth served the same purpose as all miraculous births in literature and religion, to foreshadow a mythical character, a chosen one. What's more, in "Revenge" Darth Sidious shares a story of one Darth Plagueis who "was a Dark Lord of the Sith, so powerful and so wise, he could use the Force to influence the midi-chlorians to create life. He had such a knowledge of the dark side, he could even keep the ones he cared about from dying." To me at least this strongly hinted that Plagueis engineered Anakin, using Shmi as an unwitting vessel, and this untold backstory was one of the reasons Lucas introduced midi-chlorians. Still, to prop up the mythical elements of Star Wars with factual explanations was a poor decision. As for fishy, Shmi was sold to Cliegg Lars (father of Owen, who later raised Luke) shortly after Anakin left Tattoine, who freed her and married her. She died in Episode II before the Clone Wars began, with the Battle of Geonosis and the clash of Yoda and Dooku.