Fox Butterfield's review of "Ancestors" (Book Review, April 3) was most interesting, but don't let him review any book involving math.
In making the analogy of the Qin family with Western culture, he says that they would have had to have sent 20 straight generations to Harvard. Assuming the generally accepted definition of 20 years per generation, this is an impossibility. Harvard was founded in 1636, thus allowing only c. 17 1/2 generations, even if you assume the Qin boys were admitted at birth and immediately graduated.
EDWARD P. HURLEY