very little of willpower is genetic

[Honest]

conscientiousness/'willpower' is strongly influenced by genetics per scientific studies. interestingly, it's been shown to either be uncorrelated or slightly negatively correlated with intelligence 

Although conceptually conscientiousness should be positively associated with intelligence, existing empirical data do not support this hypothesis. Most results did not reveal significant correlations of this personality dimension with various cognitive abilities (Ackerman & Heggestad, 1997). However, several recent investigations reported a negative association of the two variables (Moutafi et al., 2004, Moutafi et al., 2005). The compensation mechanism has been proposed as a possible explanation of this result (von Stumm, Chamorro-Premuzic & Ackerman, 2011). Particularly, it has been suggested that less able individuals may compensate for their lower intellectual capacity by developing a high level of conscientiousness. People with high intelligence do not need to be very conscientious as they can rely solely on their intellect to accomplish most tasks. 
https://www.sciencedirect.com/science/article/abs/pii/S1041608015001740