255.27 – Incest in the First Degree.

§ 255.27 Incest in the first degree.
A  person  is  guilty  of  incest  in  the first degree when he or she
  commits the crime of rape in the first degree, as defined in subdivision
  three or four of section 130.35 of this part, or criminal sexual act  in
  the  first  degree,  as  defined in subdivision three or four of section
  130.50 of this part, against a person whom he or she knows to be related
  to him or  her,  whether  through  marriage  or  not,  as  an  ancestor,
  descendant,  brother or sister of either the whole or half blood, uncle,
  aunt, nephew or niece.
Incest in the first degree is a class B felony.