וַיִּהְי֣וּ בְנֵי־פֶ֔רֶץ לְחֶצְרֹ֕ן מִשְׁפַּ֖חַת הַֽחֶצְרֹנִ֑י לְחָמ֕וּל מִשְׁפַּ֖חַת הֶחָמוּלִֽי׃
And the sons of Perez were: of Hezron, the family of the Hezronites; of Hamul, the family of the Hamulites.
Read midrashic interpretation of Numbers 26:21: and classical rabbinic exegesis.