INGENUOUS

artless

frank and candid

lacking in sophistication

/charcterized by an inability to mask your feelings
"An ingenuous admission of responsibility."

//showing innocent or childlike simplicity and candidness

lacking craft or subtlety

"He had been so ingenuous in their previous interactions, he felt he could trust his comments."

"It was refreshing to her such an ingenuous admission."

"He had always known he lacked the persuasive manipulative powers which others had, but to him being ingenuous was not a downfall but a positive."