The little girl next door says that she was taught to never lie because her grandpa says it is wrong. This type of mentality is an example of what moral theory?

The little girl is reflecting an authoritarian form of mentality.

Explanation:

Teaching little children not to lie is a good thing. Telling them not to lie is also good. But like the sentence suggests, the little girl is saying that her decision not to lie is based on her grandfather's teachings and not because she thinks it is wrong. This is just an example of an authoritarian form of exerting power or ideas upon the lesser weaker people.