Okla. Stat. tit. 43, § 43-128: Avoidance of marriage of incompetents

When either of the parties to a marriage shall be incapable,

from want of age or understanding, of contracting such marriage, the

same may be declared void by the district court, in an action

brought by the incapable party or by the parent or guardian of such

party; but the children of such marriage begotten before the same is

annulled, shall be legitimate. Cohabitation after such incapacity

ceases, shall be a sufficient defense to any such action.