As an attorney, I sometimes have the distasteful job of telling a client that they have no case. It really is not a happy thing. I could wish for every client to hit the jackpot, but I would be doing them no favors by allowing them to spend time and effort pursuing something which has no basis in the law.
So here, I must tell you that you probably should not pin your hopes of physical ancestry to one of the lost ten tribes of Israel on the use of nivracheu (aka nivrachu) in Genesis 12:3. The meaning you have been told, that it somehow references mixing, or grafting in, is spurious.
The Hebrew root is barak, which simply means to bless. In Hebrew, words are routinely modified to adapt to how they are used in a sentence. In this case, the letter nun is added to the front to make it a Niphal conjugation (passive or reflexive voice, depending on context), and that is further prefixed with a vav, which makes it a past perfect tense, or the idea of a done deal, what is sometimes called the prophetic perfect tense, speaking of a future event as though it were an accomplished fact.
In all of that, there is nothing remotely like a so-called special form of barak which doubles for grafted in or mixed. All you see in this passage is an ordinary, everyday Niphal conjugation of to bless. Thats just how you make words in Hebrew.
Now I am aware that some are claiming support for the grafted view from examples in various extrabiblical sources. All of these are asserting the possibility of an obscure alternative usage for the term. But in the samples typically used to promote the grafted view, Talmudic or otherwise, none of them turn out to be any good. Either the conjugation form is different, rendering the pun theory irrelevant, or an incorrect grouping of words is applied, or some other blatant mishandling of basic grammatical rules invalidates the alleged proof.
And one would have to wonder how the ordinary scribe of Israel would react to this hidden mixing concept, since so much else in the law emphasizes that mixing is bad. Using Moses as a template for spiritual realities per the book of Hebrews, one would have to conclude that God used mixing as a metaphor for impurity, idolatry, incompleteness of devotion to the pattern of worship established by God, and so forth. None of this would seem compatible with the idea of a blessing.
Furthermore, there appears to be evidence from the New Testament that such a meaning as biological mixing is quite impossible. Consider the following passage:
Gal 3:13-16 Christ hath redeemed us from the curse of the law, being made a curse for us: for it is written, Cursed is every one that hangeth on a tree: That the blessing of Abraham might come on the Gentiles through Jesus Christ; that we might receive the promise of the Spirit through faith. Brethren, I speak after the manner of men; Though it be but a man’s covenant, yet if it be confirmed, no man disannulleth, or addeth thereto. Now to Abraham and his seed were the promises made. He saith not, And to seeds, as of many; but as of one, And to thy seed, which is Christ.
Paul here seems to be saying that the blessing promised had a definite means of conveyance, faith in Christ. He further emphasizes that the blessing is not transmitted along a limitless number of separate biological lines (seeds), but is transmitted to whoever is found in Christ (the seed) through faith:
Gal 3:29 And if ye be Christ’s, then are ye Abraham’s seed, and heirs according to the promise.
Notice the order. First you belong to Christ, then you are Abrahams seed, and an heir to the promise. Not the other way around.
Now Paul recognizes that even among humans, once a contract is set, you cant add to it or take away from it. One of the ways people try to circumvent a contract is by attempting to discover an ambiguity from which they can extract some new meaning not intended by the original parties to the contract. And that is why contract law resists ambiguities. If there is an easy, obvious way to understand the plain sense of what the parties agreed to by taking the words at their face value, youre not allowed to look for hidden or secondary meanings that radically alter that plain sense meaning. The judge wont let you do that. I think thats a good rule to apply here. To bless just means what it says, to bless.
“Regarding your question about the use of the word “nivrechu” to mean more than just “blessing” but rather as “mixed” or “grafted”:
In Hebrew, Beresheit/Genesis 12:3 literally reads: “Ve’nivrechu bekah kol mishpachot ha-adamah.” “I will bless those who bless you and curse those who curse you and in you all the nations of the earth shall be mixed! The Hebrew word translated in most translations as “blessed”, is the Hebrew word “ve’nivrechu.” “ve-Nivrechu” appears only three times in the Tanak at Beresheit 12:3, 18:18 and 28:14 and all three times it speaks of how Avraham will affect the nations of the earth. This word can also mean “mixed” or “grafted” as much as it connotes blessing. This is important when one understands the greater plan of Yahuwah to fulfill His promise to Avraham and his descendants to, yes, certainly “bless” the nations but also in “how” He would do that blessing: via “grafting” or “mixing” of his seed into all the nations.
For a greater understanding of “nivrechu” you could go to,
http://yourarmstoisrael.org/Articles_new/questions/?page=summer2003&type=2
Now Gen 12:3 is not my only scriptural premise to base my beliefs on, there are many from Genesis through Revelation.
Just as a starter I recommend Jim Staley, a Pastor in St. Louis, who has a great teaching that is solid named “Identity Crisis” It’ sound scripturally or if you want to check out my web page www.forthispurpose.tv. I offer my free ebook on what was the Gospel Jesus preached...He didn't preach about his death, burial, and resurrection...yet that is the gospel traditional Christianity has preached. So what was the Gospel Jesus and his disciples preached for 3 1/2 years? My book answers that question. If your interested. But what I have found is that only if the Holy Spirit draws a person to see these truths, it just ain't going to happen. And if it doesn't, that's ok...none of my business, it's between the person and Yahweh.
However you choose to pursue or not to pursue, I am sure you are a very nice man as you showed me great respect in your thoughtful answer so I ask Yahweh to bless your relationship with Him and if I am scripturally out of order I pray Yahweh stop me from continuing on as a Bible teacher of these truths or correct me where I am wrong.