Peust notes that other factors that can obscure genetic relationships between languages include the poor state of present documentation and understanding of particular language families (historically with Egyptian, presently with Omotic).
pjˈuːst nˈoʊts ðæt ˈʌðɚ fˈæktɚz ðæt kæn əbskjˈʊɹ dʒɪnˈɛɾɪk ɹᵻlˈeɪʃənʃˌɪps bᵻtwˌiːn lˈæŋɡwɪdʒᵻz ɪŋklˈuːd ðə pˈʊɹ stˈeɪt ʌv pɹˈɛzənt dˌɑːkjuːməntˈeɪʃən ænd ˌʌndɚstˈændɪŋ ʌv pɚtˈɪkjʊlɚ lˈæŋɡwɪdʒ fˈæmɪliz hɪstˈɔːɹɪkli wɪð ɪdʒˈɪpʃən, pɹˈɛzəntli wɪð ɑːmˈɑːɾɪk.