Faith does not "come" through natural genetic processes. Faith truly has a vital link with blood—the blood of Christ, "whom God set forth to be a propitiation by His blood, through faith" (Romans 3:25). But an individual does not inherit faith through a natural bloodline; God did not see fit to encode faith in human DNA, so that it could be passed to offspring.
Christ's disciples, in asking Him to "increase our faith" (Luke 17:5), exhibit their understanding that God, not genetics, is the ultimate source of faith. Because "God shows no partiality" (Acts 10:34; see Romans 2:11), He has no proclivity to limit His giving and increasing of faith to a particular racial stock. For that reason, faith as a characteristic does not "belong" to a particular race as, say, a set of facial features is peculiar to a given race.
In His time, then, God made faith available to the Gentiles and with it, spiritual salvation, which has its taproot in faith:
Christ has redeemed us from the curse of the law, . . . [so] that the blessing of Abraham might come upon the Gentiles through Christ Jesus, that we might receive the promise of the Spirit through faith" (Galatians 3:13-14).
Peter says as much to the church gathered in Jerusalem. In Acts 11:17-18, he connects "the gift" given to the Gentiles with belief—faith—in Christ:
"If therefore God gave them [Gentiles] the same gift as He gave us when we believed on the Lord Jesus Christ, who was I that I could withstand God?" When they heard these things they became silent: and they glorified God, saying, "Then has God also granted to the Gentiles repentance to life."
God's Israel crosses natural racial or ethnic distinctions; the faithful of any race make up the Israel of God. These are the faithful who receive "the blessing of Abraham" (Galatians 3:14).