High heritability of speech and language impairments in 6-year-old twins demonstrated using parent and teacher report
Behavior Genetics (2006) - Comment
doi: 10.1007/s10519-005-9020-0  issn: 0001-8244  issn: 1573-3297  pubmed: 16485179 

Dorothy V. M. Bishop, Glynis Laws, Caroline Adams, Courtenay Frazier Norbury