(1) No other evidence is required to prove marriage of a husband and wife or that the defendant is the lawful parent of a legitimate child or has acknowledged paternity of an illegitimate child than is required to prove this fact in a civil action.
(2) The spouse and parent is a competent witness to testify in any case brought under this chapter and to a matter relevant to this chapter, including the fact of the marriage and the parentage of the child.
(3) A legally adopted child and a child whose parentage was determined in a paternity proceeding is within the provisions of this chapter and no proof other than an order of a proper court is required to prove parentage.