Longitudinal study ; Erblichkeit; Heredity; Grammar gene; FOXP2; Language and genetics ; Twin research ; Academic achievement; Language and intelligence ; Spracherwerb und neurologische Entwicklung; Language acquisition and neurological development; Sprache und Denken (Ontogenese) ; Language and thought (ontogenesis) ; Cognitive development; Language acquisition and cognitive development ; Innate ideas hypothesis; Poverty of the stimulus-argument; Lernbarkeit (von Sprache) ; Learnability (of language) ; Nature/nurture; Logisches Problem (Spracherwerb) ; Logical problem (language acquisition) ; Nativist hypothesis