To show how random gene construction is, you can look at the list of genes on Chromosome 2, which is available here:Just one mutation/squeeze play made us 'humans.'
`

Chromosome 2 - Wikipedia
You'll notice three important Hox genes for body shape and segmentation (FBXO11, PAX3, SATB2), a critical immune system gene (CTLA4), and a gene related to hereditary Parkinsonism (PARK3).