title: Genes versus environment in ocular refraction.
mesh_terms: D000328:Adult; D004200:Diseases in Twins / Q000235:genetics; D004777:Environment; D005260:Female; D005799:Genes, Dominant / Q000235:genetics; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000209:etiology / Q000235:genetics; D009426:Netherlands; D012029:Refraction, Ocular / Q000235:genetics* / Q000502:physiology; D018433:Twin Studies as Topic; D014427:Twins / Q000235:genetics