From a response by Marc Hauser to Patricia Churchland’s review of Steven Pinker’s book The Stuff of Thought:
[…] The monumental cognitive gap between mice and humans tells us that the number of homologous genes and the percentage of sequence overlap are simplistic measures of species similarity, rather than the genomic overlap telling us that humans are cognitively equivalent to mice.
We have to look to another story to explain how, given such overlap, we are so different. The point is magnified when we consider the 98% overlap with chimpanzees, and again, the spectacular differences in our cognitive abilities […].
Something to follow up to find ammunition to attack those with naive views of genes, e.g. the “gene for language”, “gene for happiness”, crowd.