This is an appeal from a judgment of the district court of Morton County, setting aside a decree of the county court of Morton County which admitted to probate the will of D. W. Elmer, deceased. The judgment of the district court directs that the estate of Elmer be administered under the laws of intestate succession of the State of North Dakota.
The will in question was executed by the deceased on the evening of January 12, 1972. The testator had been brought to the hospital by his brother, Jake Elmer, the appellant, on the previous day, at the request of the testator. It is evident from the record that the testator was a critically ill person when admitted to the hospital. He was suffering from congestive heart failure and from shortness of breath, and was very apprehensive. A dose of seventy-five milligrams of Demerol was administered to him at about 2 :50 p. m. on January 12. Demerol is a drug which affects the brain processes, and was prescribed to reduce the apprehension. About 4:30 p. m. of that day, less than two hours after the drug had been administered, and during the period of its greatest effect, the appellant, Jake, whose son was bequeathed the entire estate under the provisions of the will, spoke to the testator alone for about half an hour. Then the appellant left to obtain an attorney to have the will prepared.
Medical testimony discloses that at 4:30 p. m., the drug which had been administered would have been at its maximum in effectiveness, but that in the ordinary person those effects would have worn off to a large extent by the time of the execution of the will that evening, and that the drug would have a more lasting effect on a person in poor physical condition.
The testator had been placed in an oxygen tent at about noon on the 12th of January and the oxygen tent had been removed at some time prior to the execution of the will. Although the testator signed his name in a very legible hand on his admission to the hospital on January 11, he was wholly unable to sign his name to the will at the time of its execution, and executed it merely by making a belabored “X.” There also is testimony by the proponents of the will that it had been drawn by the attorney who was called by the appellant, and the attorney was given information as to the provisions to be put into the will by the testator himself. After the execution of the will, the attorney kept the instrument until after the death of Elmer one week later. It was not seen again by the testator after its execution.
About six days prior to the testator’s entry into the hospital, he called on his attorney on another matter, but talked about selling the farm or renting it. At that time, he made no mention of drawing a will in favor of his nephew, the son of the appellant. The appellant- testified that when he first talked to the decedent on January 12, just prior to the drafting of the will, the decedent had said, “I don’t know what to do. What shall I do?” At the time of this conversation, he was under the effects of medication and the appellant was alone with him.
One paragraph of the will provides:
“THIRD: I make no provision for my brothers, Jake N. Elmer, Henry Elmer, nor for my sisters, Lena Elmer, Rachel Martell and Marie Brown, all of whom are financially so fixed that they can well live without any benefits from my estate. . . .”
The record discloses that the brother Henry was eighty-two years of age at that time and was a retired fruit picker living in a retirement home. One of the sisters, Rachel Martel, was a widow seventy-seven years of age, in the process of purchasing a trailer home by installments. Another sister, Marie Brown, was sixty-seven years of age and making her living scrubbing and cleaning buses for a transcontinental bus company. Each had a small amount of *818savings, insufficient for support for any-prolonged period of time.
There are two main issues to be determined on this appeal, and they are so closely related that they can be considered together: (1) Was D. W. Elmer legally competent to execute a will on the evening of January 12; and (2) Was he at that time under the undue influence of his brother Jake?
Section 30-06-03, North Dakota Century Code, provides that among the issues to be tried and determined by the court, where objections are made to the probate of a will, are:
1. The competency of the decedent to make a last will and testament; and
2. The freedom of the decedent, at the time of the execution of the will, from duress, menace, fraud, or undue influence.
The district court found that at the time the will was executed the appellant, Jake, whose son was the sole beneficiary under the will, was disposed to and did exercise undue influence upon him; that the disposition of the estate as made in the will was unnatural because it excluded the testator’s brothers and sisters and all other nieces and nephews and was highly advantageous to the family of the appellant; and that the will as executed was not the free and lawful will of the deceased, but was obtained by the exercise of the undue influence of Jake N. Elmer.
Assuredly, this is a very close case. On the side of the appellant, many persuasive arguments can be made, as the dissent shows. The decedent was a successful farmer, self-reliant during his lifetime. Unless his mind was overpowered by undue influence, he had every right to dispose of his property as he chose. The persons present at the time he signed the will (the attorney and the male nurse, who witnessed the will) and the appellant (who saw him earlier in the day and just before the conference between the decedent and the attorney resulting in the drafting of the will) testified that he knew and understood what he was doing. They indicate that his inability to sign his name, and his use of an “X” instead, was due to a temporary numbness in his right thumb and forefinger.
On the other hand, it appears that the decedent spent about half an hour alone with his brother, the appellant, in the afternoon, and that during this half hour the decedent was admittedly under the influence of Demerol to a high degree. The attending physician (who did not see the patient during the crucial period, but did see him many times during his hospitalization) testified that the patient was critically ill and suffering from congestive heart failure, that this medical problem results in a deficiency oí oxygen in the brain which in turn results in a “clouding of clarity” and a reduction of acuity, that he was very apprehensive and had difficulty in breathing, and that a person in such a condition will tend to avoid other problems and take the easy way out. In order to alleviate the apprehension, the physician prescribed Demerol, which reduces the apprehension (but has no effect on the supply of oxygen to the brain), has the further effect of producing euphoria, and reduces likelihood of resistance to suggestion. The physician described “euphoria” as a “lackadaisical, happy-go-lucky, slightly airy feeling.”
The trial court concluded from the foregoing that the decedent was highly susceptible to undue influence in the afternoon when he conferred with the appellant, just before the appellant left to get the attorney who subsequently drew the will, about four hours later. By the time the will was drawn and signed, the effect of the Demerol was lessened, but the problem of oxygen supply to the brain continued, and the apprehensiveness presumably returned to some degree. More important, the medical testimony of the attending physician, who was the only expert called by either side, indicates a considerable significance in the numbness of the right hand at the time of the execution of the will. The physician *819indicates that the numbness was due to either a stroke, or a spasm of a cerebral blood vessel, occurring at the time of the signing. Upon seeing the signature of the decedent the previous day on an admission record of the hospital, and comparing it with the attempted signature on the will, the doctor said he could “hardly believe they are the signatures of the same individual they are so different,” and stated that the person making the second one was in “considerable medical and physical difficulty.”
We conclude from this testimony that the trial judge had ample reason to conclude that undue influence affected the signing of the will.
This is not to say that the members of this court, or those who sign this majority opinion, if acting as trial judges, would have arrived at the same decision. This is, as we have said, a close case on the facts.
The legal principles involved are not in dispute. They have been expounded many times, in this State and others. Our decisions include Stormon v. Weiss, 65 N.W.2d 475 (N.D.1954), and In re Burris’ Estate, 72 N.W.2d 884 (N.D.1955).
The principal holdings in these cases can be briefly summarized. There is a presumption of sanity and testamentary capacity, and the burden of proving lack of capacity is on the contestant. The ultimate question in a challenge of a will on the ground of testamentary capacity is the competency of the decedent at the time of making the will. Nephews, nieces, brothers, and sisters, and all other collateral heirs are not, because of the relationship alone, “natural objects of bounty,” as that term is used in the interpretation of wills. A signature to a will made by an “X” is valid, but the circumstances necessitating such a signature, like all the other circumstances of the making of the will, may be considered in determining the question of competency. Where undue influence is alleged to have entered into the making of the will, there may be an inference of susceptibility from domination or confidential relationship by the beneficiary of the proposed will. The ultimate question in such 'cases is whether the will is the result of undue influence on the mind of the testator at the time of the making of the will.
A lengthy annotation at 9 A.L.R.3d 15 discusses the general principles involved here, particularly as applied in cases of alleged addiction or use of alcohol and drugs, including Demerol. Parenthetically, the annotation contains at least six cases where Demerol was the drug in question, and in all of these the will was ultimately upheld, but this is of little value to us in the light of the testimony of the one expert in this case, to the effect that the effects of Demerol are variable in different individuals, and may vary widely depending upon time factors and the method of use, whether by intramuscular injection (used here) or intravenous injection, or orally. The annotation does not state the method of use in the cases cited.
While we place great reliance, as we must, on the findings of the trial court [Rule 52(a), N.D.R.Civ.P.], we must also recognize that the cutting edge of that rule is at least dulled by the fact that this case has previously been decided by two trial judges, the county judge who heard it in the first instance and the district judge who heard it de novo without a jury in the second instance, and that the first upheld the will and the latter denied it probate. While we do not have a record of the proceedings in the county court, we have heard from one of counsel that the testimony was similar in both courts.
Nevertheless, we are bound by Rule 52(a). We are bound by .it, whether we consider the decision of the lower court as conclusive upon us as to issues of fact as a jury verdict is, or whether we are bound by a slightly less severe standard, as the dissent urged in Kleinjan v. Knutson, 207 N.W.2d 247 (N.D.1973).
*820When we adopted Rule 52 from the Federal Rules of Civil Procedure, we did so with knowledge of the interpretations placed on it by the Federal courts. Although we are not compelled to follow those interpretations, they are highly persuasive and, in the interest of uniform interpretation, we should be guided by them.
A finding is “clearly erroneous” only when, although there is some evidence to support it, the reviewing court on the entire evidence is left with a definite and firm conviction that a mistake has been made. United States v. United States Gypsum Co., 333 U.S. 364, 68 S.Ct. 525, 92 L.Ed. 746 (1948). The mere fact that the appellate court might have viewed the facts differently, if we had been the initial trier of the case, does not entitle us to reverse the lower court. Nee v. Linwood Securities Co., 174 F.2d 434 (8th Cir. 1949) ; Wright & Miller, Federal Rules of Civil Procedure, Sec. 2585, p. 729 et seq.
In a case like this one, where the determination must ultimately be made in large part upon an evaluation of the credibility of the witnesses, we must be especially alert to the admonition of Rule 52(a) that—
“. . . due regard shall be given to the opportunity of the trial court to judge of the credibility of the witnesses.”
Here, the trial judge has determined, in his memorandum opinion, that the testimony of one witness, the appellant himself, is not to be given full credit. The testimony of that witness is of crucial importance. We will not say that this determination, or the decision of the trial judge on the merits, is “clearly erroneous.” Our function is not to decide factual issues de novo. Zenith Radio Corp. v. Hazeltine Research, Inc., 395 U.S. 100, 89 S.Ct. 1562, 23 L.Ed.2d 129 (1969).
This is, as we have indicated, a case where the decision might have gone either way. Where this is true, it necessarily follows that a decision either one way or the other cannot be “clearly erroneous.”
“Such a choice between two permissible views of the weight of evidence is not ‘clearly erroneous.’ ” United States v. Yellow Cab Co., 338 U.S. 338, 70 S.Ct. 177, 94 L.Ed. 150 (1949).
It is also true that it is the findings of the trial court which we must adhere to unless clearly erroneous, and not the conclusions of law or the ultimate decision made upon the basis of those findings. See Moore’s Federal Practice, Sec. 52.-05(1) and cases cited. But here, the trial court made exhaustive findings of fact, and related the factual basis for each. We are satisfied that the record supports the findings, and that the findings made compel the result ordered by the lower court. While other findings, compelling a different result, could have been made from the same evidence, they were not made here.
The findings made include all the essentials for a finding of undue influence as set out in In re Burris’ Estate, supra: the opportunity to exercise undue influence, the disposition to exercise it, the susceptibility of the decedent to the exercise of undue influence, and that the result appears to be the effect of undue influence.
The judgment of the trial court therefore is affirmed.
PER CURIAM.
VOGEL, J., was not a member of the court at the time of oral argument, but participated on the briefs. The foregoing opinion includes a summary of facts prepared by ALVIN C. STRUTZ, Chief Justice, before his death, and many of the cited authorities were collected by him. Coincidentally, the same situation occurred in our leading case of Stormon v. Weiss, N.D., 65 N.W.2d 475. See Note 1, p. 479.
ERICKSTAD, C. J., and KNUD SON and PAULSON, JJ., concur.