Does a jury's failure to instruct on lesser included offenses constitute grounds for reversal?

Even if there is an erroneous failure to instruct on lesser included offenses, that error may not be prejudicial. (People v. Sedeno (1974) 10 Cal.3d 703, 721, 518 P.2d 913. ⁶ ) The rule has been summarized this way: "If the jury is fully instructed on the factual issue raised by the defendant, and it is clear from a verdict based on such instructions that the jury necessarily resolved the factual question adversely to the defendant, then the failure to instruct on lesser included offenses will not constitute grounds for reversal." (People v. Eaker[134 Cal.App.3d 519] (1980) 100 Cal.App.3d 1007, 1013, 161 Cal.Rptr. 417 (emphasis in original), summarizing People v. Sedeno, supra, 10 Cal.3d 703, 721, 518 P.2d 913.)