The figures he quotes concern the heritability of a trait, where heritability refers to the proportion of the variance in a trait among individuals that is attributable to differences in their genes (more correctly, their genotypes).
Contrary to what he suggests, such figures do not tell us how much of a trait is due to genes and how much to the environment. To be fair, he does use the term "heritability", but not correctly. In fact, there is a long-standing consensus in biology that talk of the kind Mr James and many others use is meaningless.
Dr Terence Sullivan Ferry Lane primary school, London