565.140.  Defenses to kidnapping in the third degree. — 1.  A person does not commit the offense of kidnapping in the third degree under section 565.130 if the person restrained is a child less than seventeen years of age and:

  (1)  A parent, guardian or other person responsible for the general supervision of the child's welfare has consented to the restraint; or

  (2)  The person is a relative of the child; and

  (a)  The person's sole purpose is to assume control of the child; and

  (b)  The child is not taken out of the state of Missouri.

  2.  For the purpose of this section, "relative" means a parent or stepparent, ancestor, sibling, uncle or aunt, including an adoptive relative of the same degree through marriage or adoption.

  3.  The defendant shall have the burden of injecting the issue of a defense under this section.