If you guys know this answers me. why many physcial different in people be traced to differents in their dna

Even though humans share 100% of the same genes, the instructions contained within the genes are not entirely identical. Each person is unique. People have different hair colors, facial structures, and other traits. These differences between individuals result from very small differences in their DNA sequences. DNA also contains many so-called "housekeeping genes" that control important metabolic processes. As you will see, some of the differences in these genes can cause illness.

Although the DNA of any two people on Earth is, in fact, 99.9% identical, even a tiny difference can have a big effect if this difference is located in a critical gene.