Mo. Rev. Stat. § 566.025: Evidence that defendant has committed other charged and uncharged crimes of a sexual nature involving victims under fourteen admissible to prove propensity to commit crime, when.

In prosecutions pursuant to this chapter or chapter 568 of a sexual nature involving a victim under fourteen years of age, whether or not age is an element of the crime for which the defendant is on trial, evidence that the defendant has committed other charged or uncharged crimes of a sexual nature involving victims under fourteen years of age shall be admissible for the purpose of showing the propensity of the defendant to commit the crime or crimes with which he or she is charged unless the trial court finds that the probative value of such evidence is outweighed by the prejudicial effect.