To be sure, whether an unintended crime was the independent product of the perpetrator's mind outside of, or foreign to, the common design may, if shown by the evidence, become relevant to the question whether that crime was a natural and probable consequence of the target crime. In a given case, a criminal defendant may argue to the jury that the nontarget crime was the perpetrator's independent idea unrelated to the common plan, and thus was not reasonably foreseeable and not a natural and probable consequence of the target crime. But that would be a factual issue for the jury to resolve (People v. Chiu, supra, 59 Cal.4th at p. 162, 172 Cal.Rptr.3d 438, 325 P.3d 972 ), not a separate legal requirement.