450.9  Individual exemptions.
  In computing the tax on the net estate, the entire amount of property, interest in property, and income passing to the surviving spouse, and parents, grandparents, great-grandparents, and other lineal ascendants, children including legally adopted children and biological children entitled to inherit under the laws of this state, stepchildren, and grandchildren, great-grandchildren, and other lineal descendants are exempt from tax.
[C31, 35, §7312-d1; C39, §7312.1; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §450.9; 81 Acts, ch 147, §3, 19]
91 Acts, ch 159, §23, 24; 94 Acts, ch 1046, §10; 97 Acts, ch 1, §2, 8