This retrospective study compared the speech-language development of a pair of dizygotic twin girls during the first 2 years of life: one with typical development (Twin A) and one with atypical development (Twin B), who was later diagnosed with Rett syndrome (RTT). Audio snippets were extracted from home videos, with nearly equal representation from each child. The audio analysis focused on articulatory complexity, voice characteristics, and linguistic variability. Despite sharing the …