I'd probably argue the numbers, because I don't think that's a good explanation of how genetics would actually effect personality.
Like I've said elsewhere, genetics should give you an emotional range that you are capable of, and then environment will cultivate something within that range. Same why you might be predisposed to being tall, but lack of food, injury, and nutrition is going to have a major impact of where you fall in that range.
To add to this, I seem to recall reading that part of moral development depends of children having disputes and resolving them on their own.
Regarding personality, I think it was Personality: What Makes You The Way You Are by Daniel Nettle that claimed roughly 50% of personality is genetic.
I'd probably argue the numbers, because I don't think that's a good explanation of how genetics would actually effect personality.
Like I've said elsewhere, genetics should give you an emotional range that you are capable of, and then environment will cultivate something within that range. Same why you might be predisposed to being tall, but lack of food, injury, and nutrition is going to have a major impact of where you fall in that range.