Yichus

The biblical spelling used in Nech. 7:5 סֵפֶר הַיַּחַשׂ (Book of Lineage)[2] differs in the last letter, compared to both Yiddish and modern Hebrew (יִחוּס, sometimes ייחוס).

Although the word yichus originated in Hebrew[3][4], the term is generally accepted as a Yiddish word that has flowed into Modern English.

The Anglicized word has been transliterated as

• Yichus[5]
• Yikhes[6][7]
• Yiches[8]
• Yikhus[9]

Despite the fact that being Jewish from birth is universally accepted based on the religion of the mother[10], that same universally accepted definition says "(the tribal affiliation, tradition, customs and nusach of prayer) are determined by the Jewish father." To the obvious question[11] there is the question of why "Rabbah bar Bar Chanah"[12] and the matter of the Blasphemer, Lev. 24:10-23, not accredited to the tribe of Dan.

As far back as the Talmudic era, being son-in-law to someone widely respected was valued.[13] Subsequently, even the Yichus of being son-in-law to the son-in-law and similar lineage links were on one side, versus "meritocratic leadership based on scholarship" on the other, in the areas of "the arrangement of marriages and determination of hierarchical social distinctions."[6]

There were those who, for the above[14] and other reasons, devalued or hid it:

• Dem gonefs yikhes (The Thief's Genealogy) - a song[15]
• "In Lithuania some Jewish families hid their Yikhus (lineage)"[16]

For various reasons, Last names[27]/family names were changed, and sometimes reverted[23]. Hence certain family names, such as Cohen, are not as strongly indicative of being a Kohen as Katz.