K.S.A. 59-2114(a) controls the parameters of a consenting party in an adoption case: "Consent shall be in writing and shall be acknowledged before a judge of a court of record or before an officer authorized by law to take acknowledgments. If consent is acknowledged before a judge of a court of record, it shall be the duty of the court to advise the consenting person of the consequences of the consent. A consent is final when executed, unless the consenting party, prior to final decree of adoption, alleges and proves by clear and convincing evidence that the consent was not freely and voluntarily given. the burden of proving the consent was not freely and voluntarily given shall rest with the consenting party." The court in In re Adoption of Irons, 235 Kan. 540, 684 P.2d 332 (1984), discussed the general concepts of valid consent. The court stated that when a consent to adoption is properly acknowledged, the acknowledgement serves as prima facie proof of the validity of the consent and that the written consent was freely and voluntarily given. See 1 Elrod, Kansas Family Law Handbook 6.032B (1990); In re Adoption of Trent, 229 Kan. 224, 228, 624 P.2d 433 (1981). In order to rebut the presumption of validity there must be a showing of fraud, duress, undue influence, mistake or lack of understanding. See In re Adoption of Chance, 4 Kan. App. 2d 576, 583, 609 P.2d 232, rev. denied 228 Kan. 806 (1980).