Kansas Marriage Laws: What the State Constitution says…
Nature of marriage relation. (a) The marriage contract is to be considered in law as a civil contract between two parties who are of opposite sex. All other marriages are declared to be contrary to the public policy of this state and are void. The consent of the parties is essential. The marriage ceremony may be regarded either as a civil ceremony or as a religious sacrament, but the marriage relation shall only be entered into, maintained or abrogated as provided by law.
(b) The state of Kansas shall not recognize a common-law marriage contract if either party to the marriage contract is under 18 years of age.
Kansas Stat.ute 23-101
Source: Kansas State Constitution