"Defendant argues 'the only evidence [about Jane being disabled] was that Jane suffered from cerebral palsy and seizures, that she had difficulty speaking, and that she attended a school with special education. . . . [But o]ne of the strongest circumstances indicating that Jane lacked the mental capacity to consent is that she did not respond to defendant‘s questions asking if she liked what they were doing during the sexual assault. The jury could rationally conclude that a 15-year-old girl who had the ability to appreciate what was taking place would express some reaction to a surprise sexual assault from her grandfather in a small trailer, with her brother nearby, in the early hours of the morning. Jane's lack of response certainly suggests that she did not have the capacity to understand the consequences of defendant‘s acts or the ability to voluntarily consent to them. From her failure to react, the jury could infer she did not simply have difficulty speaking, but that her mental capabilities, in the circumstances of the offenses, prevented her from being capable of giving consent.
A further indication of Jane‘s lack of capacity to consent is found in her childlike description at trial of the sexual assault. The best she could do to explain what happened was to place shaky marks on simple diagrams to indicate where and how she was touched by defendant, and hold up ten fingers when asked about how she was touched by defendant. The impression left by her testimony was that she lacked the understanding required of one capable of giving consent and defendant knowingly took advantage of that disability. The jury could reasonably infer that an inability to articulate what happened demonstrated that Jane was not capable of appreciating what took place or freely and voluntarily participating in the acts."