B. If any person carnally knows, without the use of force, a child thirteen years of age or older but under fifteen years of age who consents to sexual intercourse and the accused is a minor and such consenting child is three years or more the accused's junior, the accused shall be guilty of a Class 6 felony. If such consenting child is less than three years the accused's junior, the accused shall be guilty of a Class 4 misdemeanor.
In calculating whether such child is three years or more a junior of the accused minor, the actual dates of birth of the child and the accused, respectively, shall be used.