lˌæ bɹˈæntʃ wʌz bˈɔːɹn nˌɪɹ nˈuː ˈɔːɹliənz, ðə sˈʌn ʌv ˌælɪɡzˈændɚ lˌæ bɹˈæntʃ ɐ ɹˌɛvəlˈuːʃənˌɛɹi wˈɔːɹ ɹˌɛdʒɪmˈɛntəl kəmˈændɚ hˌuːz fˈæmɪli hæd ˈɛmɪɡɹˌeɪɾᵻd tə luːˌiːzɪˈænə fɹʌm bɐvˈɛɹiə ænd hæd tʃˈeɪndʒd ɪts sˈɜːneɪm fɹʌmðə dʒˈɜːmən "zwˈeɪɡ" tə ðə fɹˈɛntʃ "bɹˈæntʃ," wɪð bˈoʊθ nˈeɪmz mˈiːnɪŋ "bɹˈæntʃ"ænd mɚɹˈiː dʒˈiːn pˈaɪsɹoʊz hˌuːz fˈæmɪli wʌz ʌv spˈænɪʃ ˈænsɛstɹi.
La Branche was born near New Orleans, the son of Alexandre La Branche (a Revolutionary War regimental commander whose family had emigrated to Louisiana from Bavaria and had changed its surname from the German "Zweig" to the French "Branche," with both names meaning "branch") and Marie Jeanne Piseros (whose family was of Spanish ancestry).