Jill is visiting her boyfriend's family in China. During a conversation, she points to him with her index finger, which his family doesn't seem to like. Later, her boyfriend explains that she should point with an open hand instead of using a finger. Why is this instruction needed

Gestures don't have universal meanings.

Explanation:

Gestures are interpreted differently across cultures. Some gestures could receive positive feedback in one culture while it receives negative feedback in another. In other cases, they could both receive positive feedback but the aims of the gestures could be different.

For instance, hand gestures are interpreted differently. In the United States, a "thumbs up" gesture receives a positive response and is seen as a subtle sign of praise or approval. In the middle east however, a "thumbs up" gesture is found offensive.

Another example is snapping the fingers. Snapping the fingers could have different meanings, one being that one just remembered a forgotten thought/fact. In other instances, it could be used to call for a person's attention. In the former, the gesture is perceived positively while in the latter instance, it could be considered a rude gesture as in the case of calling for a waiter's attention with a snap of fingers.