IQ-gene

In the angry debateover how much of IQ comes from the genes that children inherit from par-entsand how much comes from experiences,one little fact gets overlookeD.no

one has identifiedany genes(other than those that cause retardation)that affect intelligence.Soresearchers led by Robert Plomin of London's Institute of Psychiatry decided to

look for some.Theyfigured that if you want to find a"smart gene,"you should look insmart kids.They therefore examined the DNA of students like those who are sobright

that they takecollege entrance exams four years ear-ly-and still score at Princeton-caliberlevels. The scientists found what they sought."We have,"saysPlomin,"the first

specific gene everassociated with general intelligence."

Plomin's colleaguesdrew blood from two groups of 51 children each,all 6 to 15 years old and livingin six counties around Cleveland.In one group,the average IQ is 103.All

the children arewhite .Isolating the blood cells,the researchers then examined each child'schromosome 6 .Of the

37 landmarks onchromosome 6 that the researchers looked for,one jumped out:a form of genecalled IGF2R occurred in twice as many children in the high-IQ group as in the

average group-32percent versus 16 percent. The study,in the May issue of the journalPsychological Science, concludes that it is this form of the IGF2R gene thatcontributes

to intelligence.

Some geneticists seemajor problems with the IQ-gene study.One is the possibility that Plomin'sgroup fell for"chopsticks fallacy".Geneticists might think they'vefound a

gene for chopsticksflexibility,but all they've really found is a gene more common in Asiansthan,say,Af-ricans.Similarly,Plomin's IQ gene might simply be one that is more

common in groupsthat em-phasize academic achievement."What is the gene that they've foundreflects ethnicity?"asks ge-neticist Andrew Feinberg of Johns Hopkins

University."Thatalone might explain the link to intel-ligence,since IQ tests are known forbeing culturally sensitive and affected by a child's environ-ment."AndNeil Risch of

Standford University points out that if you look for 37 genes ona chro- mosome,as the researchers did,and find that one is more common insmarter kids,that might re- flect

pure chance ratherthan a causal link between the gene and intelligence.Warns Feinberg:"Iwould take these findings with a whole box of salt."Whatdoes"some"in the second sentence of paragraph one stands for?

A.Parents.

B. Children.

C. Experiences.

D.Genes.