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WASHINGTON (Reuters) - An unusual genetic study supports the argument that good teachers make a difference and shows that poor teachers may do damage, even to gifted students, researchers said on Thursday.
The study, published in the journal Science, showed that effective teachers help kids with the best genes read better, while poor teachers brought down all the children in a classroom to the same mediocre level.
The findings by behavioral geneticist Jeanette Taylor at Florida State University and colleagues could influence the debate in Congress, the White House and school districts across the United States about measuring the quality in schools.
"In circumstances where the teachers are all excellent, the variability in student reading achievement may appear to be largely due to genetics. However, poor teaching impedes the ability of children to reach their potential," Taylor and colleagues concluded.
To tease out the effects of genes and environment, the researchers turned to the time-tested model of twins. Identical twins share all their DNA, while fraternal twins share about half, or as much as any brother or sister.
Their theory: if one identical twin does better than his or her sibling in a different classroom, much of the difference must be due to the teacher.
They studied 280 identical twin pairs and 526 fraternal twin pairs in the first and second grades from a diverse selection of Florida schools.
To determine teacher quality, they used Oral Reading Fluency test scored for the entire classroom of each twin.
"(It's) a timed measure of how many words children can read in a passage," Taylor said in a Science podcast.
They checked to see how many more words children could read at the end of the year compared to the beginning.
"We felt that was a reasonable estimate of teacher effectiveness," Taylor said.
When teachers were good, the genes really mattered. If one identical twin excelled with a good teacher, the other did too. But if one twin had a strong teacher and the other twin had a weak teacher, twins with strong genetic potential did just so-so in the poor teacher's class.
"Better teachers provide an environment that allows children to reach their potential," Taylor said.
"As state and national policy increasingly focuses on teacher quality, the effect that teachers have on the strong documented genetic foundation of reading is an important question," the researchers wrote.
While great teachers do not guarantee success, they said, policymakers need to realize that good teaching is important, even for gifted children.
One weakness of the study -- the researchers threw out data from identical twins who happened to be in the same classroom who scored differently from one another on the reading test. Taylor said she did not know how many such cases there were.
Reporting by Maggie Fox, editing by Stacey Joyce