Since chimpanzees have more chromosomes then we do it's just as believable ...or the pufferfish or lizards or...
Man vs. mouse
-- Mice and humans both have about 30,000 genes - and share 99% of them - but the mouse genome is shorter than that of humans (2.5 billion letters compared with 2.9 billion) -- -- About 1,200 new genes have been discovered in the human because of mouse-human genome comparisons.
-- Mice have many more olfactory genes compared to the human. Smell matters for mice, especially for sex and mating; they also have more genes involved in reproduction (such as aphrodisin, which stimulates mating behaviour in males) and immunity.
-- It might be said that we are essentially mice without tails - but we even have the genes that could make a tail.
-- 90 percent of genes associated with disease are identical in the human and the mouse, supporting the use of mice as model organisms.