I dissent.
In this case, we must apply Probate Code section 6454,1 which provides in relevant part: “For the purpose of determining intestate succession by a person . . . from or through a foster parent or stepparent, the relationship of parent and child exists between that person and the person’s foster parent or stepparent if both of the following requirements are satisfied: [^] (a) The relationship began during the person’s minority and continued throughout the joint lifetimes of the person and the person’s foster parent or stepparent. [H] (b) It is established by clear and convincing evidence that the foster parent or stepparent would have adopted the person but for a legal barrier.”
The Courts of Appeal have disagreed as to the necessary duration of the “legal barrier” that the statute references. (§ 6454, subd. (b).) Construing section 6454’s predecessor, the Sixth District held that the legal barrier had to exist only when adoption was attempted or contemplated. (Estate of Stevenson (1992) 11 Cal.App.4th 852, 865-866 [14 Cal.Rptr.2d 250] (Stevenson).) Construing the same statute, Division Five of the Second District expressly rejected Stevenson and held that the legal barrier must have existed throughout the lives of the child and the foster parent or stepparent. (Estate of Cleveland (1993) 17 Cal.App.4th 1700, 1709-1713 [22 Cal.Rptr.2d 590] (Cleveland).)
Essentially agreeing with Cleveland, the majority rewrites the statute so as to render it virtually inapplicable to adult foster children or stepchildren, who seldom (if ever) could demonstrate a lifetime legal barrier to adoption. This narrow construction is neither compelled by the words of the statute nor necessary to effectuate the Legislature’s intent. On the contrary, Stevenson’s interpretation, which has the express endorsement of the commission that drafted the statute for the Legislature, is both more logical and more consistent with the available indicia of legislative intent. Moreover, the advantages that the majority claims for its construction are largely illusory. *219Accordingly, I cannot join in the majority’s restrictive revision of section 6454.
I. Discussion
A. The Statutory Language Is Reasonably Susceptible to the Stevenson Interpretation.
The “primary and overriding goal of all statutory interpretation” is to determine the Legislature’s intent. (Pacific Southwest Realty Co. v. County of Los Angeles (1991) 1 Cal.4th 155, 167 [2 Cal.Rptr.2d 536, 820 P.2d 1046].) In making this determination, we first look to the words of the provision in question. “When the language is clear and there is no uncertainty as to the legislative intent, we look no further and simply enforce the statute according to its terms. [Citations.]” (DuBois v. Workers’ Comp. Appeals Bd. (1993) 5 Cal.4th 382, 387-388 [20 Cal.Rptr.2d 523, 853 P.2d 978] (DuBois).) However, when the language is susceptible to more than one reasonable interpretation, we look to a variety of extrinsic aids, including legislative history, and consider the consequences that will flow from a particular interpretation. (Dyna-Med, Inc. v. Fair Employment & Housing Com. (1987) 43 Cal.3d 1379, 1387 [241 Cal.Rptr. 67, 743 P.2d 1323] (Dyna-Med); People v. Woodhead (1987) 43 Cal.3d 1002, 1008 [239 Cal.Rptr. 656, 741 P.2d 154].)
The majority does not assert that the language of section 6454 is clear, unambiguous, and susceptible to only one reasonable interpretation. Rather, the majority simply declares that its construction “is consistent with the words” of the statute. (Maj. opn., ante, at p. 212.) Indeed, to bolster its construction, the majority rewrites the language of subdivision (b) to require proof that the legal barrier was “the necessary cause of the failure to adopt.” (Maj. opn., ante, at pp. 206, 212.) The majority also establishes an admittedly implied requirement of proof that “an intent to adopt . . . continued” until the death of the foster parent or stepparent. (Id. at p. 212.) These requirements are not apparent from the words of the statute. That the majority does not believe the plain meaning of the statutory language compels its construction is also evident from its discussion of the statute’s purpose, as reflected in legislative history. (Id. at pp. 212-214.) This discussion would be unnecessary if the majority’s reading of the statute were the only reasonable one.
Nor could the majority correctly assert that its construction is the only reasonable one. Where evidence conclusively shows that the foster parent or stepparent attempted to adopt the child at some point and that a legal barrier *220thwarted the attempt, one can reasonably conclude that the foster parent or stepparent “would have adopted the [child] but for a legal barrier.” (§ 6454, subd. (b).) This conclusion would be reasonable whether or not a legal barrier also existed after (and before) the unsuccessful adoption attempt. Of course, in any given case, the probate court as the trier of fact, not this court, should decide in the first instance whether the evidence in support of this conclusion is “clear and convincing.” (§ 6454, subd. (b).)
B. The Majority’s Construction Is Inconsistent With the Statutory Language Viewed in Context.
In determining the meaning of section 6454, subdivision (b), we must consider its language “in the context of the entire statute . . . and the statutory scheme of which it is a part.” (DuBois, supra, 5 Cal.4th at p. 388.) “[Statutes or statutory sections relating to the same subject must be harmonized, both internally and with each other, to the extent possible. [Citations.]” (Dyna-Med, supra, 43 Cal.3d at p. 1387.)
The majority’s construction of section 6454, subdivision (b), is inconsistent with the provision’s language viewed in the context of the entire statute. The majority essentially reads into the statute two qualifiers for the “legal barrier” requirement of subdivision (b), declaring that the legal barrier to adoption must have: (1) “begun during the foster child or stepchild’s minority”; and (2) “continued throughout the joint lifetimes of the foster child or stepchild and the foster parent or stepparent . . . .” (Maj. opn., ante, at p. 212.) Notably, subdivision (a) of section 6454 uses virtually identical language in expressly setting forth these same qualifiers for the relationship that must have existed between the foster parent or stepparent and the child. It requires that the relationship: (1) “began during the person’s minority”; and (2) “continued throughout the joint lifetimes of the person and the person’s foster parent or stepparent.” (§ 6454, subd. (a).) Thus, in subdivision (a), the Legislature has demonstrated that, if it intends to establish these requirements, it knows how to draft statutory language expressly doing so. The Legislature’s omission of this language from subdivision (b) therefore suggests that it did not intend to establish these qualifiers for the “legal barrier” requirement. “[W]hen different words are used in contemporaneously enacted, adjoining subdivisions of a statute, the inference is compelling that a difference in meaning was intended.” (People v. Jones (1988) 46 Cal.3d 585, 596 [250 Cal.Rptr. 635, 758 P.2d 1165], original italics.) Instead of following this principle and giving effect to the different wording of the two subdivisions, the majority essentially rewrites subdivision (b) using the language of subdivision (a).
By rewriting section 6454 to require a continuous, lifetime legal barrier to adoption (and a continuous, lifetime intent to adopt), the majority violates *221the “cardinal rule” of statutory construction that prohibits us from adding provisions to statutes. (Security Pacific National Bank v. Wozab (1990) 51 Cal.3d 991, 998 [275 Cal.Rptr. 201, 800 P.2d 557].) Under the guise of interpretation, we may not “insert qualifying provisions not included” in section 6454. (People v. One 1940 Ford V-8 Coupe (1950) 36 Cal.2d 471, 475 [224 P.2d 677]; see also California Fed. Savings & Loan Assn. v. City of Los Angeles (1995) 11 Cal.4th 342, 349 [45 Cal.Rptr.2d 279, 902 P.2d 297]; Code Civ. Proc., § 1858 [in construing statute, court may not “insert what has been omitted”].) Unlike the majority, then, I would not rewrite section 6454 by reading the express requirements of subdivision (a) into subdivision (b).
C. The Purposes Underlying the Probate Code Do Not Justify the Majority’s Construction.
The majority declares that its reading of section 6454 “suits” one of the purposes underlying the Probate Code: to pass the estates of intestate decedents in accordance with their likely intent at the time of death.2 (Maj. opn., ante, at p. 212.) The majority asserts that, where proof exists of both a continuous legal barrier to adoption and a continuous intent to adopt, we can readily conclude that a decedent, had he or she made a will, would have left property to the foster child or stepchild. By contrast, the majority declares, “it is hard" to make this conclusion where the legal barrier existed only at the time the adoption was attempted or contemplated. {Id. at p. 213.) Under the latter circumstances, we can make no inference regarding the existence of a parent-child relationship between a decedent and a foster child or stepchild other than at the time of the adoption attempt. {Ibid.)
As I read section 6454, the Legislature has adequately addressed the majority’s concern about carrying out a decedent’s likely intent by expressly imposing in subdivision (a) the additional requirement that “[t]he relationship began during the person’s minority and continued throughout the joint lifetimes of the person and the person’s foster parent or stepparent.” (§ 6454, subd. (a).) Courts have strictly construed this provision. In Estate of Claffey (1989) 209 Cal.App.3d 254, 257-260 [257 Cal.Rptr. 197] (Claffey), the court held that the continuous parent-child relationship subdivision (a) requires must be a family relationship like that of a biological parent and child. Thus, the majority is needlessly concerned that, under Stevenson’s interpretation, a foster child or stepchild could share in an estate despite a significant change in his or her relationship with a decedent; the other statutory requirements *222preclude this result and ensure that the statute will not apply to a foster child or stepchild who had become no more than “a friend” of the decedent.3 (Maj. opn., ante, at p. 213.)
In disagreeing with the majority, I emphasize the narrowness of the question before us: whether the absence of a legal barrier to petitioner’s adoption after she reached the age of majority precludes her, as a mutter of law, from establishing that decedent would have adopted her “but for a legal barrier.” (§ 6454, subd. (b).) By enacting section 6454, the Legislature indicated that the probate court, as the fact finder, ordinarily should decide whether a decedent would have adopted a foster child or stepchild but for a legal barrier. Contrary to this intent, the majority removes this question from the probate court’s consideration in all but the rare cases where both a continuous legal barrier to adoption and a continuous intent to adopt existed. In so doing, the majority weighs certain evidentiary factors in an attempt to make factual determinations about a decedent’s likely intent.4 In my view, this is the function of the probate court considering the entire evidentiary record in a given case, not of this court in the abstract. If the evidence is weak, then the probate court may conclude as a factual matter that the requirements of the statute have not been met. That a legal barrier to adoption did not exist continuously during adulthood is a circumstance for the probate court to weigh in determining whether the foster parent or stepparent would have adopted the child but for a legal barrier. It is not a basis for completely removing the issue from the fact finder’s consideration.
The majority next declares that its construction furthers another purpose of the statute: to pass the decedent’s estate “efficiently and expeditiously.” (Maj. opn., ante, at p. 213.) It will, the majority asserts, at least reduce “marginal claims . . . based on little more than an assertion that [a legal barrier] existed only at a time at which adoption was contemplated or *223attempted.” (Ibid.) A contrary interpretation, the majority worries, will require the probate court to determine claims “ ‘from the stalest sort of evidence,’ ” without benefit of the decedent’s testimony or corroborating testimony from disinterested third parties. (Ibid.)
For three reasons, I reject the majority’s reliance on the supposed efficiency of its interpretation. First, the other requirements of the statute provide ample protection against marginal claims and ensure defeat of a claim “based on little more than an assertion that [a legal barrier] existed only at the time at which adoption was contemplated or attempted.” (Maj. opn., ante, at p. 213.) As I have previously noted, subdivision (a) of section 6454 requires proof that the parent-child relationship “began during the person’s minority and continued throughout the joint lifetimes of the person and the person’s foster parent or stepparent.” And, under subdivision (b), the proof that the foster parent or stepparent would have adopted the person but for a legal barrier must be “clear and convincing.” As the majority notes (maj. opn., ante, at p. 215), the California Law Revision Commission (Commission), in its recent recommendation that the Legislature expressly codify Stevenson, relied on precisely these requirements to conclude that Stevenson’s interpretation of section 6454 “should not lead to an increase of manufactured claims . . . .” (Recommendation: Inheritance by Foster Child or Stepchild (Oct. 1997) 27 Cal. Law Revision Com. Rep. (1997) p. x7 [preprint copy].) The majority does not contest this conclusion. (Maj. opn., ante, at p. 215.) Thus, we need not rewrite the statute and impose new requirements to prevent marginal claims from succeeding.
Second, the majority overstates the extent to which the goal of efficiency should guide our inquiry. By opening up a decedent’s estate to claims of foster children and stepchildren, and by making these claims depend on proof of highly fact-specific requirements, section 6454, by its very nature, is inconsistent with the goal of efficiency. Had efficiency been the Legislature’s sole concern, it would not have enacted section 6454. Instead, it would have left California law unchanged and in accord with that of other states by simply omitting foster children and stepchildren from the intestacy statutes. Thus, by enacting section 6454, the Legislature demonstrated that, at least in this one area, it was not primarily concerned about efficiency.5
Third, the majority’s reading is no more efficient than Stevenson’s. Both constructions would require the probate court to rely on the same “stale” *224evidence without the benefit of testimony from either the decedent or disinterested third parties. Indeed, the majority’s interpretation is perhaps the less efficient one, because it will require consideration of even more of the very evidence that the majority finds suspect. Under the majority’s approach, the parties must introduce evidence as to whether, at every moment during the joint lifetimes of the decedent and the foster child or stepchild, there was a legal barrier to adoption. Proof of this fact may require, for example, evidence that there was no point during the child’s minority when his or her natural parents would consent to adoption, and no point during adulthood when his or her spouse would consent. Under the majority’s approach, the parties must also introduce evidence as to whether, at all times until death, decedent had an intent to adopt. Thus, the legislative goals the majority cites do not justify its revision of the statute.
D. The Majority’s Construction Is Inconsistent With Indicia of the Legislature’s Intent.
Not only does the majority overstate the extent to which certain legislative goals support its construction of section 6454; it understates the importance of other indicia of legislative intent that support Stevenson’s contrary construction. The Commission’s published comment to section 6454 states: “Section 6454 applies, for example, where a foster child or stepchild is not adopted because a parent of the child refuses to consent to the adoption. See also Estate of Lind, 209 Cal.App.3d 1424 . . . (1989); Estate of Claffey, 209 Cal.App.3d 254 . . . (1989).” (Cal. Law Revision Com. com., 53 West’s Ann. Prob. Code (1997 pocket pt.) foll. § 6454, p. 181.) The Commission first issued the comment in substantially this form when it drafted and recommended enactment of a new Probate Code in 1989, which included section 6454’s identical 6 (Recommendation Proposing New Probate Code (Dec. 1989) 20 Cal. Law Revision Com. Rep. (1990) p. 1470.) The comment thus constitutes persuasive evidence of the Legislature’s intent in subsequently enacting the Commission’s recommendation into law. (People v. Garfield (1985) 40 Cal.3d 192, 199 [219 Cal.Rptr. 196, 707 P.2d 258].) In two ways, it indicates that Stevenson, not Cleveland, provides the correct statutory interpretation.
First, contrary to the legislative intent the comment evidences, the majority’s construction of section 6454 excludes most foster children and stepchildren who were not adopted because a natural parent refused to consent. The *225majority correctly observes that some legal barriers to adoption may apply to adult foster children or stepchildren. (Maj. opn., ante, at pp. 214-215.) However, the likelihood that one (or some combination) of these barriers will continuously exist throughout the joint lifetimes of a decedent and a foster child or stepchild seems remote at best. Thus, the majority’s construction will, in the words of the Commission, “preclude inheritance by virtually all adults from ... a foster parent or stepparent.” (Recommendation: Inheritance by Foster Child or Stepchild, supra, 27 Cal. Law Revision Com. Rep. (1997) p. x6 [preprint copy].) It will render the statute inapplicable as a matter of law to foster children and stepchildren who were not adopted during minority because a natural parent refused to consent, except in the rare case where the child is still a minor at the time of (or reached the age of majority shortly before) decedent’s death.
The majority’s response on this point is unconvincing. The majority asserts that exclusion of most adults from the reach of the statute is consistent with legislative intent because the statute “seems to have been designed to apply only in exceptional circumstances.” (Maj. opn., ante, at p. 216.) However, the majority cites no support for its assertion about the intended scope of the statute. In any event, as previously noted, the other requirements of section 6454 limit its scope, by requiring that the parent-child relationship began during the child’s minority, that the relationship continued throughout the joint lifetimes of the child and the foster parent or stepparent, and that the proof the latter would have adopted the child but for a legal barrier be clear and convincing. These requirements independently render the statute applicable only in exceptional circumstances. Even if we assume, then, that this was the Legislature’s intent, we need not exclude virtually all adults in order to achieve consistency with that intent.
Second, the comment’s approving citation of Estate of Lind (1989) 209 Cal.App.3d 1424 [257 Cal.Rptr. 853] (Lind) and Claffey, supra, 209 Cal.App.3d 254, suggests the Stevenson interpretation is correct. In Lind, the probate court had dismissed claimant’s will contest on demurrer for lack of standing. On appeal, claimant argued in part that he had standing because he would take under section 6454’s predecessor if the will contest succeeded. Claimant’s foster parents had taken him into their home shortly after his birth, where he resided until he entered the military in 1942, and they had treated him as their natural son throughout their lifetimes. (Lind, supra, 209 Cal.App.3d at pp. 1429, 1432.) The court held that claimant could invoke the statute where his pleadings and the evidence in opposition to the demurrer showed only an attempt to adopt after claimant had become an adult and a legal barrier (statutory prohibition of adult adoptions) existing only at that time. (Id. at pp. 1433-1434.) For the guidance of the probate court, the *226appellate court also discussed the evidentiary showing claimant would have to make to establish his claim under the statute, stating: “If an attempt to legally adopt was made, it can be inferred it failed because of a legal barrier, absent evidence the attempt was aborted for nonlegal reasons (such as a change of heart, lack of funds, or mere lethargy), provided a definite legal barrier can be shown to have existed at the time of the attempted adoption. If [claimant] is able to demonstrate to the court by clear and convincing evidence that [his foster parents] would have adopted him in 1942, the state’s prohibition of adult adoptions at that time would constitute a sufficient legal barrier to the adoption.” (Id. at p. 1436.) Thus, notwithstanding that claimant had lived with his foster parents from shortly after his birth, the court held that he could invoke the statute with proof of a single, unsuccessful attempt to adopt him after he became an adult. The court did not suggest he would also have to show that there was a legal barrier to adoption either while he was a minor or after the 1951 repeal of the prohibition on adult adoptions. Citation of Lind in the comment to section 6454 thus indicates that, as the Legislature understands the statute, the record in Lind may satisfy the requirements of section 6454. The interpretation of the Stevenson court, which relied on Lind, is consistent with the Legislature’s understanding. (See Stevenson, supra,. 11 Cal.App.4th at pp. 865-866.) The majority’s construction is not; under it, the Lind record would be insufficient even to state a claim and survive demurrer.
Claffey also supports the Stevenson interpretation, although perhaps less directly. Claimants in Claffey were minors when their father married decedent in 1935. (Claffey, supra, 209 Cal.App.3d atpp. 255-256.) Decedent died intestate in 1985, decades after the younger claimant reached adulthood. (Id. at p. 256.) Claimants sought to share in the estate under section 6454’s predecessor, alleging only that decedent would have adopted them but for their natural mother’s refusal to consent. (Claffey, supra, 209 Cal.App.3d at p. 256.) They did not allege that a legal barrier to their adoption existed during their adulthood. The appellate court affirmed a judgment against claimants based on the jury’s finding that a continuous family relationship had not existed between claimants and decedent. (Id. at p. 259.) Alternatively, the court held that claimants had failed to establish the “legal barrier” requirement of the statute. (Id. at p. 259, fn. 6.) Notably, in reaching this conclusion, the court did not hold that the absence of evidence of a legal barrier to adoption during claimants’ adulthood defeated their claim as a matter of law. Rather, it relied on the jury’s factual finding that, “although there was a legal barrier to adoption” (id. at p. 257), “there was not clear and convincing evidence [decedent] would have adopted [claimants] if the mother had consented.” (Id. at p. 259, fn. 6.) Thus, the court did not construe the statute as requiring that a legal barrier to adoption existed continuously *227until decedent’s death, although this construction would have easily disposed of the case. Citation of this case in the comment to section 6454 therefore provides further support for Stevenson’s construction.
E. The Consequences of the Majority’s Construction Are Contrary to the Legislature’s Purpose.
When a question of statutory construction is uncertain, we must consider the consequences that will flow from a particular interpretation. (Dyna-Med, supra, 43 Cal.3d at p. 1387.) We “should not adopt a statutory construction that will lead to results contrary to the Legislature’s apparent purpose.” (Western Oil & Gas Assn. v. Monterey Bay Unified Air Pollution Control Dist. (1989) 49 Cal.3d 408, 425 [261 Cal.Rptr. 384, 777 P.2d 157].)
The majority’s construction óf section 6454 violates this principle because it will lead to results contrary to the Legislature’s purpose. As I have previously noted, because a continuous legal barrier rarely exists after the foster child or stepchild reaches adulthood, the majority’s construction renders section 6454 inapplicable to virtually all adult foster children and stepchildren, no matter how strong the evidence of the decedent’s intent. Thus, under the majority’s interpretation, even where an adoption attempt during the child’s minority failed because the child’s natural parents would not consent, and repeated adoption attempts during the child’s adulthood failed because of some other legal barrier, section 6454 would not apply if, during some relatively brief period (e.g., five years or even one year), no legal barrier to adoption existed. Also, under the majority’s construction, even where a legal barrier defeated repeated and continuous adoption attempts throughout the child’s adulthood, section 6454 would not apply if no legal barrier to adoption existed during the child’s minority or if, for any reason (such as respect for the child’s natural parents), decedent had no intent to adopt during that period. This result finds no support in the language of the statute, which requires on its face only that the relationship between the child and the foster parent or stepparent began during the child’s minority. (§ 6454, subd. (a).)
Indeed, the majority’s construction will exclude even certain minors whom the Legislature no doubt intended to include. Under the majority’s approach, section 6454 is inapplicable unless, from the outset of the parent-child relationship between a decedent and the foster child or stepchild, both a legal barrier to adoption and an intent to adopt existed. Thus, the majority would exclude a foster child or stepchild whose foster parents or stepparents could have initially adopted the child, but did not form the intent to do so until some later point during the child’s minority—e.g., after the natural *228parents lost touch with the child, moved away, or died—when a legal barrier prevented it. I cannot conclude that these consequences are consistent with the Legislature’s intent.
II. Conclusion
For all of the reasons set forth above, I would reverse the judgment of the Court of Appeal.
Unless otherwise indicated, all further statutory references are to the Probate Code.
For the sake of simplicity, “decedent” refers to the foster parent or stepparent through whom the claimant seeks to share in an estate. The statute may also apply where the intestate decedent is not the foster parent or stepparent.
For the same reason, I disagree with the majority that the “legal barrier” requirement has “independent meaning” as the requirement that “assures” the relationship between the foster child or stepchild and the foster parent or stepparent “was tantamount to” an adoptive one. (Maj. opn., ante, at p. 216.) Even if the majority is correct in assuming the Legislature intended the requirements of section 6454 to provide this assurance, the “continuous relationship” requirement of subdivision (a), as judicially construed, already serves this function, at least in significant part.
For example, quoting Cleveland, the majority declares: “[T]hat [an adult] adoption may not be ‘so important . . . would weigh against the conclusion that’ the foster parent or stepparent ‘considered’ the foster child or stepchild ‘to be one of his . . . “children.” ’ ” (Maj. opn., ante, at p. 214, quoting Cleveland, supra, 17 Cal.App.4th at p. 1710.) Again quoting Cleveland, the majority also declares that a failure to adopt during adulthood, despite the absence of a legal barrier, “would signify that what might once have approached a parent-child relationship . . . might well have suffered a ‘change in [its] nature or quality’ in the interim.” (Maj. opn., ante, at p. 213, quoting Cleveland, supra, 17 Cal.App.4th at p. 1710.)
The majority asserts that the Commission’s purpose in drafting the 1983 revisions to the Probate Code was to establish new rules that would pass an estate consistent with the decedent’s likely intent “in a ‘more efficient and expeditious’ manner. [Citation.]” (Maj. opn., ante, at p. 209.) However, in a summary of its report to the Legislature, the Commission explained that “many,” not all, of its proposed changes were being “made to clarify and simplify probate law, . . . and to promote national uniformity of law.” (Tent. Recommendation Relating to Wills and Intestate Succession (Nov. 1982) 16 Cal. Law Revision Com. Rep. *224(1982) p. 2311, italics added.) Even under the majority’s construction, section 6454 does not serve these ends.
As the majority correctly notes, in proposing new probate provisions, the Commission was acting at the express direction of the Legislature. (See maj. opn., ante, at pp. 208-209.)