*289The opinion of the court was delivered by
Fatzer, J.:This was a proceeding commenced in the probate court to determine whether the decedents’ joint will was contractual.
On October 2, 1929, Newell A. and Bertha O. Thompson, husband and wife, executed a joint will, which, omitting the attestation clause, reads:
“Joint Last Will and Testament of Newell A. Thompson and Bertha O. Thompson, Husband and Wife.
“We, Newell A. Thompson and Bertha O. Thompson, Husband and Wife, of Geary County, Kansas, being of sound mind, memory and discretion, and being — under no restraint, do make, publish and declare this, as and for our joint Last Will and Testament:
“First: We direct that out of our estate our funeral expenses, expenses of last sickness and all other of our just and lawful, debts be paid.
“Second: In the event of the death of either of us, the survivor shall take all of our property, real, personal and mixed, whether the same be owned by us, jointly or severally.
“Third: We make no provision for our children, Ray Thompson and Fern Thompson, leaving it to the survivor of us to make such provision as he or she sees fit.
“Fourth: Upon the death of either of us, the survivor shall pay the funeral expenses and expenses of the last sickness of the deceased one, and all — lawful debts of the one deceased.
“Fifth: In the event of the death of either of us, the survivor shall act as executor or executrix, and it is our request that no bond shall be required of such executor or executrix, for the execution of his or her trust.
“Sixth: We hereby revoke all former wills or codicils thereto, made by us or either of us.
“In Testimony whereof we have hereunto subscribed our names, at Junction City, Kansas, this 2nd day of October 1929.
“/s/ Newell A. Thompson
“/s/ Bertha O. Thompson”
On October 12, 1966, Newell executed a subsequent will purporting to revoke the former will. Bertha, although living, did not join in executing the subsequent will, or consent thereto.
On December 30, 1967, Newell died and his will dated October 12, 1966, was admitted to probate. The probate court elected on Bertha’s behalf to take under the law and not under the terms of Newell’s October 12, 1966, will, she being incapacitated.
On May 18, 1968, Bertha died and the joint will she and Newell executed on October 2, 1929, was admitted to probate.
On November 12, 1968, the administrator c. t. a. of Bertha’s *290estate filed a petition for allowance of claim in Newell’s estate alleging that the will entered into and executed on October 2, 1929, between Bertha and Newell was a joint, mutual, and contractual will whereby the survivor of either of them should take all of the property owned by them jointly or severally, and that Newell breached such contract by the execution of his subsequent will not in accordance with the provisions of the joint, mutual, and contractual will of October 2, 1929. The prayer was for judgment in a sum equal to the entire residue of Newell’s estate remaining after payment of all his debts, and after deducting the portion theretofore set aside by the probate court to Bertha and her estate.
The executor of Newell’s estate denied that the joint will of October 2, 1929, was a mutual and contractual will of Bertha and Newell.
When the action was heard in the district court no testimony was presented or offered by the parties to the proceeding. Upon consideration of the joint will of October 2, 1929, the district court made findings of fact and conclusions of law. The court’s findings are substantially in accord with those factual recitations heretofore set forth. Conclusions 8 and 9 of the court read:
“The court finds that the will executed October the 2d, 1929, is contractual in nature. The court further finds that paragraphs 1, 2, 4, 5 and 6 are paragraphs included in most wills, if not all, and do, because said will is joint, use the plural pronouns in referring to the parties to the will, and this is done without exception.
“The court then looked at the third paragraph of said will, which states as follows: ‘We make no provision for our children, Ray Thompson and Fern Thompson, leaving it to the survivor of us to make such provision as he or she sees fit.’ The court believes and finds that by the exclusion of the children of the parties hereto, these being their only children, that agreement had to be reached between the parties prior to the will’s being executed.’’ (Emphasis supplied.)
In harmony with the foregoing conclusions, the district court directed the probate court of Geary County to act in accordance with its findings and conclusions with respect to the petition filed in Newell’s estate. Thereafter, Newell’s executor perfected this appeal.
The sole issue before this court is whether the joint will was made pursuant to- a contractual agreement. Joint execution of a will does not render the will irrevocable. The making of a will so as to render it irrevocable must be on the basis of a contractual agreement. Such contractual agreement may be shown by extrinsic evidence (In re Estate of Wade, 202 Kan. 380, 449 P. 2d 488), or such *291agreement may be shown or implied to exist by the terms of the will itself. The terms of a will may show an implication that its execution was the product of a preexisting agreement. (In re Estate of Chronister, 203 Kan. 366, 454 P. 2d 438.) The fact a will contains no reference to an agreement is not conclusive. A contract may be implied from the known circumstances under which the parties execute a joint will, such as their family relationship as reflected by the will itself, its terms and its execution, and the intention of the testators as gathered from the four corners of the instrument itself. In such a case, extrinsic evidence is not admissible for the purpose of proving otherwise.
In In re Estate of Chronister, supra, this court, after a painstaking review of the many cases of this state in which wills were claimed to be contractual, Mr. Justice Fontron, speaking for the court, stated the following basic rules:
“. . . (1) Whether a will is contractual, be it a joint will or one of separate wills, is a question of fact which must be established by proof. (2) The mere fact that a will is joint does not in and of itself establish it to be the result of a preexisting agreement. (3) A joint and mutual will and the terms and provisions thereof, may be considered sufficient as circumstantial evidence to establish that it was executed pursuant to an agreement. (4) Where a joint will shows on its face by the terms and provisions thereof that it is contractual in character, extrinsic evidence is not admissible for the purpose of proving otherwise. (5) Where there is ambiguity from the language used in a joint will as to whether or not it is based on a contract, extrinsic evidence is admissible to establish either the existence or nonexistence of a contract.” (1. c. 372.)
We are of the opinion that the will itself, based upon an examination of its terms, and its execution, evidences Bertha and Newell reached a full understanding and agreement as to the terms of their joint will prior to its execution. The use of plural pronouns, the identical disposition of their property to the survivor, the mutual exclusion of heirs, devisees and legatees, the provision for ultimate disposition of their property by the survivor “as he or she sees fit,” and their joint revocation of all former wills or codicils thereto, sufficiently evidences an understanding between the joint testators by which they intended to bind themselves. (In re Estate of Chronister, supra, p. 373.)
The appellant argues that the third provision of the will was merely to acknowledge the existence of the children, and was not evidence of an agreement or understanding between Bertha and *292Newell. The district court did not so find, and we believe its determination to be correct. Ray and Fern Thompson were the only children of the parties and under the will they were to be provided for by the survivor “as he or she sees fit.” We ask the same question as was asked in Lewis v. Lewis, 104 Kan. 269, 178 Pac. 421:
“. . . How could such a will be voluntarily executed if there was no agreement or understanding that it would be made? The will itself, its terms, and its execution, are evidence that such a contract was made . . .” (1. c. 273.)
And so here. We do not presume, under the attending circumstances, that a father and mother would disinherit their only children by written instrument, unless they had a prior agreement or contract with each other that the survivor would make such provision for their benefit as he or she saw fit.
The intention of the testators can be gleaned from the four comers of the instrument and it may be said the will was executed pursuant to a contractual agreement. The parties reached agreement as to the disposition of their estate upon the death of either of them, that the survivor be left free to make such provision for the children as he or she might see fit. Such a provision could only have been reached by agreement of the parties. (In re Estate of Tompkins, 195 Kan. 467, 407 P. 2d 545; Beall v. Hardie, 177 Kan. 353, 279 P. 2d 276.)
Bertha survived Newell, and thereby performed her part of the contract, but Newell breached their agreement when he executed his subsequent will in October, 1966.
Under the facts and circumstances, the district court was justified in finding the terms of the will showed a contractual agreement was reached between the parties when the joint will was executed, on the basis of the factors enumerated in the Chronister case. The judgment is affirmed.