OPINION OF THE COURT
ALDISERT, Circuit Judge.
Sun Wen Chen and Wen Hui Gao, husband and wife, petition for review of an order of the Board of Immigration Appeals (“BIA”) that reversed the Immigration Judge’s (“IJ”) grant of asylum and withholding of removal. Petitioners contend that they qualify for asylum and withholding of removal because they have a well-founded fear of persecution under China’s one-child policy should they be returned to China. This petition requires us to decide whether a husband may qualify for asylum on the well-founded fear that his wife may be persecuted under a coercive population control policy, a question of first impression in this Court. We hold that the husband may stand in his wife’s shoes to bring such a claim. On the merits, we will grant the petition for review on Petitioner Chen’s asylum claim.
I.
Chen and his wife Gao are Chinese citizens from the Fujian province. Both entered the United States -without valid entry documents' — Chen in 1991 and Gao in 1997. Chen applied for asylum within a month of his arrival, alleging that he feared persecution because of his parents’ active support of the students’ democratic movement. Gao applied for asylum more than two years after her arrival. Both Chen and Gao’s applications were denied, and their cases were referred to immigration court.
Chen and Gao married in the United States, and Gao gave birth to their child, a boy, on May 3, 1999. Their claims were consolidated, and the IJ held a merits hearing on July 24, 2000. Before the IJ, Chen contended that his prior application for asylum had been prepared without his approval by an organization he had asked to help him obtain work authorization. He explained that, notwithstanding statements on his application, he was not seeking asylum on the basis of his parents’ activities. Rather, Chen requested asylum and withholding of removal because of the possibility that his wife would face a forced abor[104]*104tion or sterilization under China’s coercive population control policy. Gao requested asylum on the same grounds. Both Petitioners testified that they hoped to have more children and were physically able to do so.
The IJ granted asylum and withholding of removal. He found Gao’s application time-barred, denying her contention that her case fell into the changed circumstances exception given the birth of her child. See 8 U.S.C. § 1158(a)(2)(D). Chen’s application was timely, however, and the IJ found that he could stand in his wife’s shoes for purposes of his asylum claim. The IJ found that the couple had “a well-founded fear of future persecution” that was “less than a clear probability, but ... certainly more than speculative in view of the family planning policy of limiting the number of children in [Petitioners’ home region], especially males.” He granted Chen asylum, and also granted Gao asylum derived from her husband’s status. He found both entitled to withholding of removal as well.
The BIA reversed the IJ’s decision, concluding that “the respondents failed to sustain the burden of proof.” The Board stated that “respondents did not submit any evidence specifically addressing the treatment of children born outside of China,” and that “[t]he Department of State [Profile of Asylum Claims and Country Conditions for 1998] mentions the apparent absence of a national policy regarding children born abroad....” The BIA further commented that “[t]he Department of State ... indicates that the coercive population control policies are not uniformly applied and may be enforced using numerous non-persecutory methods, including economic incentives and education.... ” The BIA concluded that “[i]n light of the variance of enforcement in China, the possibility of non-persecutory methods of enforcement, and the uncertainty about how a child born abroad is treated under the policy, we find that the respondents did not sustain the burden of proving eligibility for asylum or the more stringent burden applicable to withholding of removal.”
Chen and Gao’s petition was timely filed in the United States Court of Appeals for the Second Circuit, and was properly transferred to this Court on March 21, 2005. See 8 U.S.C. §§ 1252(b)(1) & (2).
II.
To qualify for asylum, a petitioner must show that he is a “refugee” as defined by the Immigration and Nationality Act (“INA”). 8 U.S.C. § 1158(b)(1)(A). This requires a showing that he has suffered past persecution because of “race, religion, nationality, membership in a particular social group, or public opinion,” or that he has a well-founded fear of future persecution on these grounds. 8 U.S.C. § 1101(a)(42). Congress amended the definition of “refugee” in 1996 to include the following provision:
[A] person who has been forced to abort a pregnancy or to undergo involuntary sterilization, or who has been persecuted for failure or refusal to undergo such a procedure or for other resistance to a coercive population control program, shall be deemed to have been persecuted on account of political opinion, and a person who has a well founded fear that he or she will be forced to undergo such a procedure or subject to persecution for such failure, refusal, or resistance shall be deemed to have a well founded fear of persecution on account of political opinion.
8 U.S.C. § 1101(a)(42)(B).
A party seeking asylum bears the burden of proving that he satisfies the definition of “refugee.” 8 U.S.C. [105]*105§ 1158(b)(1)(B)(1). He may do this by demonstrating a well-founded fear of persecution on the basis of a privileged ground. See 8 U.S.C. § 1101(a)(42). To establish a well-founded fear of future persecution, an asylum-seeker must show that he has a subjective fear and that his fear is objectively reasonable. See Zubeda v. Ashcroft, 333 F.3d 463, 469 (3d Cir.2003). The “[djetermination of an objectively reasonable possibility [of persecution] requires ascertaining whether a reasonable person in the alien’s circumstances would fear persecution if returned to the country in question.” Id.
III.
Before considering the details of Chen’s asylum claim, we note that we are unable to review the IJ’s denial of Gao’s application for asylum. We lack jurisdiction to review a discretionary refusal to allow an asylum-seeker the benefit of the “changed circumstances” exception to the one-year timeliness requirement. See 8 U.S.C. § 1158(a)(3); Sukwanputra v. Gonzales, 434 F.3d 627, 634 (3d Cir.2006). In this case, Petitioners argue that the BIA “did not fulfill its obligation to determine whether Gao’s application was timely,” and that therefore we have jurisdiction to reach the issue. This argument is based on a faulty premise. As the BIA points out in its opinion, Petitioners did not identify any errors in the IJ’s finding; as a result, the BIA had no obligation to review the IJ’s timeliness determination. It now stands beyond our reach.
Only Chen’s claim, then, is rightly before us. Chen’s petition for asylum, however, is based on the threat to his wife. He contends that his wife has a well-founded fear of involuntary sterilization or forced abortion, and that her fear may be imputed to him. We must determine whether such a petition may succeed.
A.
The spouse of an asylee may obtain derivative asylum status under 8 U.S.C. § 1158(b)(3), but the provision for derivative asylum does not allow one spouse to stand in the shoes of the other and to independently obtain asylum based on a threat to the other spouse. The BIA, however, has allowed a husband to obtain asylum when his wife has been persecuted under China’s one-child policy, even though the wife remained in China. Matter of C-Y-Z-, 21 I. & N. Dec. 915, 920 (BIA 1997). In C-Y-Z- the BIA, sitting en banc, held that “forced sterilization of one spouse ... is an act of persecution against the other spouse.” Id. at 919. This Court has never determined the permissibility of the BIA’s interpretation in C-Y-Z-. Although we discussed the C-YZ- ruling in Cai Luan Chen v. Ashcroft, 381 F.3d 221, 227 (3d Cir.2004), we found it unnecessary to decide whether the Board’s view was permissible because the petitioners in Cai Luan Chen were not married and therefore, we held, fell outside the scope of the BIA’s ruling.1 The viability of the BIA’s determination that one spouse’s qualification for asylum may be imputed to the other spouse is squarely before us now.2
[106]*106We accord Chevron deference to “an agency’s construction of the statute which it administers.” Chevron U.S.A., Inc. v. Natural Res. Def. Council, Inc., 467 U.S. 837, 842, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984); United States v. Mead Corp., 533 U.S. 218, 227, 121 S.Ct. 2164, 150 L.Ed.2d 292 (2001) (stating that Chevron deference is appropriate “when it appears that Congress delegated authority to the agency generally to make rules carrying the force of law, and that the agency interpretation claiming deference was promulgated in the exercise of that authority”). The INA provides that the “determination and ruling by the Attorney General with respect to all questions of law shall be controlling.” 8 U.S.C. § 1103(a)(1). This power extends to provisions of Title 8, Chapter 12 (“Immigration and Nationality”) “and all other laws relating to the immigration and naturalization of aliens.” Id. The Attorney General, in turn, has “vested the BIA with power to exercise the discretion and authority conferred upon the Attorney General by law in the course of considering and determining cases before it.” INS v. Aguirre-Aguirre, 526 U.S. 415, 425, 119 S.Ct. 1439, 143 L.Ed.2d 590 (1999) (citation omitted). The BIA’s interpretations of the INA made in the course of case-by-case adjudication therefore are entitled to Chevron deference. Id.
Following the familiar Chevron two-step, we ask first “if the statute is silent or ambiguous with respect to the specific issue” of law in the case before us. Chevron, 467 U.S. at 843, 104 S.Ct. 2778. In assessing this, we “emplo[y] traditional tools of statutory construction” to determine whether “Congress had an intention on the precise question at issue.” Id. at 843 n. 9, 104 S.Ct. 2778. If Congress’ intent on the precise question is not evident, we move to the second step, where “the question for the court is whether the agency’s answer is based on a permissible construction of the statute.” Id. When Congress has left a gap in a statute, implicitly leaving the administering agency responsible for filling that gap, “a court may not substitute its own construction of a statutory provision for a reasonable interpretation made by the administrator of an agency.” Id. at 844, 104 S.Ct. 2778. Chevron deference embodies the judgment that agencies, rather than courts, ought to serve as gap-fillers in situations of statutory silence. See Arent v. Shalala, 70 F.3d 610, 619 (D.C.Cir.1995) (Wald, J., concurring).
B.
Turning to the case at bar, we consider the BIA’s interpretation in C-Y-Z-, 21 I. & N. Dec. at 918, in which it agreed with the parties before it that “the husband of a sterilized wife can essentially stand in her shoes and make a bona fide and non-frivolous application for asylum based on problems impacting more intimately on her than on him.” As we pointed out in Cai Luan Chen, 381 F.3d at 225, the BIA “did not explain the basis for this conclusion,” instead observing that the “position [was] not in dispute” because of a concession by the government. C-Y-Z-, 21 I. & N. Dec. at 918. In a subsequent case, the Court of Appeals for the Second Circuit concluded that this absence of rationale made it impossible to determine the permissibility of the BIA’s interpretation in C-Y-Z- and so remanded to the BIA, holding off evaluating C-Y-Z- s rule “[u]n-til the BIA has clarified why it established spousal eligibility....” Lin v. Department of Justice, 416 F.3d 184, 192 (2d Cir.2005).3 [107]*107The BIA responded to the Second Circuit’s exhortations in In re S-L-L-, 24 I. & N. Dec. 1, 3 (BIA 2006), in which it reaffirmed its holding in C-Y-Z- and provided an extensive defense and explanation of its determination that “a husband whose wife was forcibly sterilized could establish past persecution” under 8 U.S.C. § 1101(a)(42).4
Under Chevron’s, step one, we must determine whether 8 U.S.C. § 1101(a)(42)(B) is “silent or ambiguous” as to the status of asylum-seekers whose spouses undergo forced abortion or sterilization. As the BIA notes, this section of the INA contains no explicit reference to spouses. S-L-L- 24 I. & N. Dec. at 5. Silence on a particular matter germane to the provisions of a statute suggests a gap of the sort that the administering agency may fill. Notwithstanding our suggestion in Cai Lnian Chen, 381 F.3d at 226, that § 1101(a)(42)(B)’s expression “other resistance to a coercive population control program” could apply to resistance by spouses, we see nothing in the statute evincing Congressional intent to establish a particular policy regarding spousal eligibility. We also do not believe that the existence of derivative asylum status under a statute implies that Congress intended to foreclose additional pathways to asylum specific to spouses.
Of course, a statute’s silence on a given issue does not confer gap-filling power on an agency unless the open question is in fact a gap — an ambiguity tied up with the provisions of the statute. An agency cannot read a statute discussing topic X to confer a power over unrelated topic Y just because the statute fails to mention topic Y. But that is not the situation here. Section 1101(a)(42)(B) establishes that forced abortion and sterilization constitute persecution. In C-Y-Z-, as explained by S-L-L-, the BIA interprets the scope of that persecution, holding that it extends to the other spouse as well. The C-Y-Z- rule thus fleshes out an issue germane to the application of § 1101(a)(42)(B) that was not addressed by Congress, and so poses no Chevron step one problem.
C.
The BIA’s interpretation also is permissible under Chevron’s step two, according to which we must leave the Board’s rule intact if it constitutes a “reasonable interpretation” of the relevant statutory provisions. Chevron, 467 U.S. at 844, 104 S.Ct. 2778. In assessing the permissibility of the BIA’s interpretation, we first note that the Board’s rule was not based on § 1101(a)(42)(B)’s provision allowing relief for an individual who exercises “other resistance to a coercive population control program” — although the BIA suggested that non-spouse partners might obtain relief under that portion of the statute. S-L-L-, 24 I. & N. Dec. at 6. The BIA also does not suggest that the word “person” as used in § 1101(a)(42)(B) can be read to include a marital “entity.” Instead, as the Board explains in S-L-L-, it recognizes that § 1101(a)(42)(B) does not address spouses, but, based on its notion of the marital relationship and its knowledge of China’s one-child policy, it concludes that the scope of this particular type of persecution extends to both spouses. S-L-L-, 24 I. & N. Dec. at 7.
The BIA’s interpretation stems from its conclusion that, when one spouse is subjected to forced abortion or sterilization, it “naturally and predictably has a profound [108]*108impact on both parties to the marriage.” Id. The Board offers three principal explanations for this conclusion: First, that the forced abortion and sterilization “depriv[e] a couple of the natural fruits of conjugal life, and the society and comfort of the child or children that might eventually have been born to them.” Id. (quoting Matter of Y-T-L-, 23 I. & N. Dec. 601, 607 (BIA 2003)). Second, that the husband “suffers emotional and sympathetic harm arising from his spouse’s mistreatment and the infringement on their shared reproductive rights.” Id. (citing our opinion in Cai Luan Chen, 381 F.3d at 225-226). And third, that in China, “such Government action is explicitly directed against both husband and wife for violation of the Government-imposed family planning law and amounts to persecution of both parties to the marriage.”5 Id. As the BIA makes clear in S-L-L-, the C-Y-Z- rule would not apply in the hypothetical case where the spouse does not oppose the forced abortion or involuntary sterilization of his wife.6 Id. at 8. Where the C-Y-Z- rule does apply, it allows the forced abortion or involuntary sterilization of one spouse to be imputed to the other spouse.
We conclude that the BIA has exercised its delegated gap-filling authority reasonably. In a great many cases, forced abortion or involuntary sterilization of one spouse will directly affect the reproductive opportunities of the other spouse, and so the BIA is not unreasonable in considering the loss to the second spouse of the “natural fruits of conjugal life, and the society and comfort of the child or children that might eventually have been born to [him].” S-L-L-, 24 I. & N. Dec. at 7. And persecution of one spouse can be one of the most potent and cruel ways of hurting the other spouse — so the BIA’s emphasis of “sympathetic harm” is not misplaced. Id. It also is not unreasonable for the BIA to consider evidence that China conceives its punishments for violations of its one-child policy as directed against married couples rather than just the party subject to forced abortion or sterilization.7 The BIA was not unreasonable in holding, based on these rationales, that the scope of the harm resulting from the enforcement of a population-control policy by forced abortion and involuntary sterilization extends to both spouses.
D.
The legislative history does not run counter to our decision. In passing Amendment 601(a) of the Illegal Immigration Reform and Immigrant Responsibility Act (IIRIRA) of 1996, which added to 8 U.S.C. § 1101(a)(42)(B) text specifically allowing for relief in cases of forced abortion or sterilization, Congress acted to reverse the BIA’s holding in Matter of Chang, 20 I. [109]*109& N. Dec. 38 (BIA 1989); see H.R.Rep. No. 104-469(1), at 173 (1996) (“The primary intent of [the relevant section of the IIRIRA] is to overturn several decisions of the Board of Immigration Appeals, principally Matter of Chang and Matter ofG-.”). In Chang, the BIA had held “that implementation of the Chinese Government’s ‘one couple, one child’ policy did not constitute persecution on account of one of the five reasons enumerated in [8 U.S.C. § 1101(a)(42)] of the Immigration and Nationality Act.” S-L-L-, 24 I. & N. Dec. at 2. In response, Congress “amended the statutory definition of ‘refugee’ to broaden the number of individuals eligible for asylum in connection with coercive family-planning policies such as China’s.” Lin, 416 F.3d at 187. According to the House Report, Congress did not intend “to protect persons who have not actually been subjected to coercive measures or specifically threatened with such measures, but merely speculate that they will be so mistreated in the future.” H.R.Rep. No. 104-459(1), at 174. This did not stop Congress, however, from providing relief for individuals with a well-founded fear of future forced sterilization or abortion. 8 U.S.C. § 1101(a)(42)(B). C-Y-Z- did nothing to alter the point on the spectrum of decreasing probability at which a well-founded fear dissipates into mere speculation. Instead, C-Y-Z- broadened the scope of persecution recognized when a well-founded fear of forced abortion or sterilization exists — or when either has occurred in the past. We are not convinced that Congress, in expanding asylum to include more reproductive rights-based claims, intended to define the outer limits of relief in such cases. We also note that the recent repeal of the 1,000-person per year cap on grants of asylum suggests a desire on the part of Congress to make asylum a less exclusive form of relief.
E.
A final issue remains before we move on to the text of the BIA’s opinion in the case at bar. C-Y-Z- and S-L-L- both involved allegations of past persecution, rather than a well-founded fear of future persecution, and some of the text in each of those opinions is specific to situations of past persecution. In the case before us, the petitioners contend that they have a well-founded fear of future persecution, but do not allege past persecution. We consider the rule of C-Y-Z- to be no less applicable to claims based on future persecution. As S-L-L- explains, the C-Y-Z- rule is based on the BIA’s conclusion that the harm of a forced abortion or involuntary sterilization is directed at and falls on both spouses. This is no less true when the persecution lies exclusively in the future.
IV.
Having established that a petitioner may qualify for asylum on the basis of a well-founded fear that his spouse may face forced abortion or sterilization, we now turn to the text of the BIA decision before us. We review the BIA’s findings of fact under the deferential substantial evidence standard. Guo v. Ashcroft, 386 F.3d 556, 561 (3d Cir.2004). Under this standard, its “findings of fact are conclusive unless any reasonable adjudicator would be compelled to conclude to the contrary.” 8 U.S.C. § 1252(b)(4)(B).
Different standards apply to our review of the BIA’s legal determinations. As discussed above, Chevron deference guides our review of BIA constructions of the INA. On the other hand, when we review “the BIA’s application of legal principles to undisputed facts, rather than its underlying determination of those facts or its interpretation of its governing statutes, our review is de novo.” Yi Long [110]*110Yang v. Gonzales, 478 F.3d 133, 141 (2d Cir.2007). As Judge Calabresi of the United States Court of Appeals for the Second Circuit has put it, “BIA errors of law are not excused by the fact that a hypothetical adjudicator, applying the law correctly, might also have denied the petition for asylum, nor can factual findings supporting such a denial be assumed on the basis of record evidence not relied on by the BIA.” Jin Shui Qiu v. Ashcroft, 329 F.3d 140, 149 (2d Cir.2003).
In the event that we grant a petition for review, the remedy depends upon the precise type of review we exercise. If we grant a petition for review on the grounds that the BIA’s decision was not supported by substantial evidence, we reverse the BIA decision—remanding with the understanding “that a reasonable fact-finder would have to conclude that the requisite fear of persecution existed.” INS v. Elias-Zacarias, 502 U.S. 478, 481, 112 S.Ct. 812, 117 L.Ed.2d 38 (1992). On the other hand, if the BIA’s error is a legal one subject to de novo review, “we will vacate BIA conclusions.” Qiu, 329 F.3d at 149. Thus, “insofar as the BIA either has not applied the law correctly, or has not supported its findings with record evidence,” we may grant a petition for review even though “a perfectly reasonable fact-finder could have settled upon” the same ultimate decision as was reached by the BIA. Id.
In the case before us, we review de novo the BIA’s application of the legal standard of § 1101(a)(42) to the facts as it found them. The BIA based its decision on three factual findings, as it makes evident in the sentence summarizing its rationale: “In light of the variance of enforcement in China, the possibility of non-persecutory methods of enforcement, and the uncertainty about how a child born abroad is treated under the policy, we find that the respondents did not sustain the burden of proving eligibility for asylum.” We find that these three factual findings, even if absolutely true, would not support the Board’s decision to deny asylum in this case. Therefore we find it unnecessary to determine whether the record supports the BIA’s factual findings.
Chen seeks asylum based on future persecution, and so must demonstrate both a subjective fear of persecution and that his fear is objectively reasonable. 8 U.S.C. § 1158(b)(1)(B). Given that the IJ found Chen’s testimony credible and the BIA has not questioned that finding, we will accept that Chen demonstrated a subjective fear that his wife would be persecuted if she returned to China. Our analysis therefore focuses on whether Chen has demonstrated that his fear is objectively reasonable.
To satisfy his overall burden, Chen is not required to demonstrate anything close to certainty that he will be persecuted, or that persecution is more likely than not. On the contrary, a one in ten chance of persecution would frighten a reasonable person. See INS v. Cardoza-Fonseca, 480 U.S. 421, 431, 107 S.Ct. 1207, 94 L.Ed.2d 434 (1987) (endorsing the statement that if “it is known that in the applicant’s country of origin every tenth adult male person is either put to death or sent to some remote labor camp,” then “it would be only too apparent that anyone who has managed to escape from the country in question will have well-founded fear of being persecuted upon his eventual return” (citation omitted)). Indeed, “fear is objectively reasonable even if there is only a slight, though discernible, chance of persecution.” Yang, 478 F.3d at 141 (citation omitted).
[111]*111B.
The BIA erred in concluding that Chen did not meet his burden of proof based only on the findings that enforcement of China’s one-child policy is “not uniformly applied,” that “not all methods of enforcement involved forced abortion, sterilization, or other forms of persecution,” and that the treatment of children born outside China is uncertain. The BIA’s conclusion was legal error. The BIA’s findings, summed together, amount to a determination that persecution is not an assured fact. The BIA must address the degree of uncertainty that Chen may face persecution; it is not enough to find that some uncertainty exists. The overall observation that future persecution is uncertain verges on a truism; it does not impugn Petitioner’s claim.8
V.
At oral argument, the government suggested that denial of asylum was the only viable outcome in this case because Petitioners presently have only one child, even though they testified that they can and hope to have more. This argument was not discussed in the briefs or by the BIA, and so we do not reach this issue.9 Furthermore, we will not discuss withholding of removal at this juncture. The BIA did not analyze withholding of removal in its opinion, having previously determined that Chen did not meet his burden of proving entitlement to asylum.10
******
For the foregoing reasons, the petition for review will be GRANTED as to Petitioner Chen’s asylum claim. This matter will be remanded to the BIA for further proceedings consistent with the discussion set forth in this opinion.