Erblichkeit; Heredity; Grammar gene; FOXP2; Language and genetics ; Twin research ; Körpersprache; Chronemics; Kinetik; Kinesics; Nonverbal communication ; Kindersprache (pathol.) ; Child language (pathol.) ; Specific language impairment; SLI; Dysgrammatismus (Kindersprache) ; Dysgrammatism (child language) ; Handicapped language acquisition