Meanings of frank boyishness in English

He was again, however, impressed by the almost frank boyishness of her manner as she said:

There was a frank boyishness about this young man, and his manner reminded her of Edwardes.

Her pagan simplicity, her frank boyishness, and her absolute unconsciousness of self, appealed to him irresistibly.

Here was an air almost of frank boyishness, a smile of pleasant friendliness, with just enough of flushing cheek to show womanliness and warm blood.