I am frequently asked if a certain surname is "Jewish".
Sometimes the person would put it in different words: "I have such and such surnames in my family. Doest it mean that I am Jewish?
My answer to the first question is: There is not such a thing as a "Jewish surnames"; there are surnames that are or have been used by Jews. But any one of those names may be or have been used by non-Jews.
To the second question I say: No, you cannot tell if you are Jewish or not ONLY by your surname or by the surnames of your ancestors.
I will explain later the rationale to my answers.
But before that let me give you here my strictly personal view – not scholarly nor based on any Jewish canon - on the question that lies behind the above question. The real question people want to ask is: "Am I a Jew?"
To answer this question you must make up your mind and decide if you want to know if you are a Jew in you hart (i.e. between you and God) or if you are seen by the others as a Jew?
If the first case is your case, why should you care if your surname is Buzaglo, Yekutieli, Sprintsak or Cruz, Espirito Santo and Oliveira? The surname doesn't make you a Jew. It is YOU that make you a Jew or not.
If what matters to you is if the others see you as Jew, try to ask yourself why this is important to you.ople that av
I know I am giving extreme examples. I know that you may want to be accepted by the others as a Jew for positive and practical reasons. For instance to be counted for a Jewish quorum (minyan) or to be able to marry according to the Jewish Law. If this is the case, and if you have decided that you want to be part of "clal Yisrael), then you always may have recourse to conversion and sometimes you may be able to prove by your ancestry, with documents of course and not only by hear saying, that you may be accepted as a Jew, according to the Halachah, without a conversion. I don't see anything wrong with conversion. But I do believe that you don't change the contents of a bottle by changing the label. Our sages said: "Don't look at the container, but only at its contents".
This said – and I repeat it is not a rabbinical opinion, because I am far from being a rabbi or a Jewish scholar – let's go back to some basics about surnames.
As far as the 18th century civil registration was not mandatory in most parts of the World. Nor where there strict rules to determine the surname of a new born.
In a simple way, the evolution of name giving was as follows:
As you see, all those surnames were originally nicknames (in Portuguese "alcunha", from the Arabic Al-Kunya, in Hebrew "Kinui"). If you read the ketubah of my marriage, you will see that my name there is "Issar ben Zeev hamekuneh Steinhardt". "Hamekuneh" means known as or whose kinui is.
IWhat happened was that when civil registration with family surnames became mandatory each Jew was attributed an arbitrary name. Those who could afford to bribe the registrar would get a name such as Blum (flower); others had to content themselves with Schwarzkopf (Blackhead).
I They also changed their Portuguese given names for new Hebrew names. They also adopted the toponymic of their place of origin as a surname.
The bottom line is that surnames can help you in genealogical research and with a clearly documented family tree you may eventually find that one or more of your ancestors have been New-Christians (Anusim) or even Jews. Only by the name you usually cannot.