Carl Zimmer writes in the NYT in "The Search for Genes Leads to Unexpected Places:"
Edward M. Marcotte is looking for drugs that can kill tumors by stopping blood vessel growth, and he and his colleagues at the University of Texas at Austin recently found some good targets — five human genes that are essential for that growth. Now they’re hunting for drugs that can stop those genes from working. Strangely, though, Dr. Marcotte did not discover the new genes in the human genome, nor in lab mice or even fruit flies. He and his colleagues found the genes in yeast.
I pointed out that in terms of genetic similarity, humanity and yeast weren't really all that different in a National Review article in 1999, "Chimps and Chumps," one of the earlier expressions of my constant theme of "genetic relativism:"
Ms. [Natalie] Angier hopes future studies prove we are more closely related to bonobos than to common chimps. Even Richard Wrangham and Dale Peterson, the dour authors of "Demonic Males: Apes and the Origins of Human Violence" ask, "Those loving bonobos -- did we pick the wrong primate to evolve from?" Dr. De Waal asserts that the news about the bonobo lifestyle "commands attention because the bonobo shares more than 98 percent of our genetic profile … making it as close to a human as, say, a fox is to a dog. The split between the human line of ancestry and the line of the chimpanzee and the bonobo is believed to have occurred a mere eight million years ago." ...
Fifth, the oft-cited 98% figure for shared DNA is less impressive than it looks. Most DNA is unused, so natural selection never changes it. Another big chunk of your personal DNA controls the basics of earthly carbon-based life, and is extremely common across multitudinous organisms. Thus, one study found we share 70% of our DNA with yeast! Perhaps if you don't have a great ape around, you can scrape by letting a packet of Fleischmann's Quick-Rise pinch-hit as your role model. De Waal's statement that a chimp is as genetically similar to a human as a fox is to a dog may be true, but it should remind us of the striking number of gene-driven differences seen merely among dog breeds. A collie is identical to a pit bull in all but a tiny fraction of its genes, yet the two breeds differ radically in size, shape, behavior, mentality, and personality. Small genetic differences can have big consequences.
On the other hand, a collie and a pit bull are more similar to each other than they are to, say, an octopus. And a collie and an octopus would be more genetically similar to each other than to, say, copper-based lifeforms on Epsilon Eridani IV.
The question: "Is X similar to or different from Y?" is extremely relativistic.
And that's true for races, siblings, even identical twins, who might differ in, say, a half-dozen genes due to copying errors, along with other types of non-genetic differences.
When you study examples of twins, you notice that there are often consistent differences between them. For example, a glance at the basketball statistics of the 1970s All-Stars Dick and Tom Van Arsdale shows that Dick was consistently a little bit better than Tom over their 12 year NBA careers. For example, to take the most context-independent statistic, Dick made .790 of his freethrows, while Tom made .762. Dick shot .464 on two pointers, while Tom shot .433. Dick averaged 34.5 minutes per game over his career while Tom averaged 30.9 minutes. (In their high school class, Dick was the valedictorian, while Tom had the third highest GPA.)
The differences between Dick and Tom were relevant to NBA general managers. For instance, Dick was drafted 10th in the 1965 NBA draft, while Tom was drafted 11th, which, looking back on their long careers, was the correct order.
On the other hand, in a lot of ways, Dick and Tom Van Arsdale were awfully similar.
I apply the same relativistic framework for thinking about more contentious issues, such as race. My basic approach is to make sure I'm right by pointing out the tautological nature of all questions about similarities and differences: "It depends upon what you want to know." When you keep that in mind at all times, it's not terribly hard to think accurately and insightfully. If you can figure out what the right question is, it's much easier to get the right answer.
Indeed, that's why I'm right about racial questions so much more frequently than other pundits. It's easy to figure things out if you have an intellectually sophisticated basis for your thinking. In contrast, the conventional wisdom is based on an embarrassingly crude mindset.