Tennessee Code Title 39. Criminal Offenses § 39-15-302

(1) The person's natural parent, child, grandparent, grandchild, uncle, aunt, nephew, niece, stepparent, stepchild, adoptive parent, adoptive child; or

(2) The person's brother or sister of the whole or half-blood or by adoption.

(b)(1) Except as provided in subdivision (b)(2), incest is a Class C felony.

(2) If the victim of the offense is a minor, incest is a Class B felony and, notwithstanding title 40, chapter 35, the defendant shall be punished as a Range II offender; however, the sentence imposed upon the defendant may, if appropriate, be within Range III but in no case shall it be lower than Range II.