Kinsey graded sexual orientation on a six-point scale. 1 being completely straight, 6 being completely gay. That makes 2 mostly straight, 3 bisexual, and 4 mostly gay. There are limitations to every linear scale, not allowing for deviation of any kind from the linear idealization. Kinsey had a fair idea of how to categorize sexual orientation, though, and was far ahead of his research contemporaries.
