 SPOILER: The first draft of the script also explained the mystery  surrounding Anakins conception. In the confrontation scene between  Anakin and Palpatine (where Palpatine confesses to Anakin he is  Darth Sidious), he would also explain that he used the power of the  Force to will the midichlorians to start the cell divisions that  created Anakin. This explanation was later deemed unnecessary by  George Lucas (qv) and subsequently cut.