Complex sentence: Tone is frequently an areal rather than a genealogical feature: a language may acquire tones through bilingualism if influential neighboring languages are tonal or if speakers of a tonal language shift to the language in question and bring their tones with them.
Split into simpler sentences: Tone is frequently an areal rather than a genealogical feature. That is, a language may acquire tones through bilingualism if influential neighboring languages are tonal, or if speakers of a tonal language shift to the language in question, and bring their tones with them.