Many of the differences between human genomes are actually in “promoter” regions. For a gene to be synthesized into a protein a little enzyme has to come over and bind to a spot next to the gene and transcribe the sequence into mRNA.
Other differences are in regions that don’t seem to affect traits at all. There’s a lot of leftover DNA in our genomes from endoviruses, transposons and other events in our evolutionary history. Sometimes the DNA in those regions randomly mutates into something useful and evolution will start acting on it.
Many of the differences between human genomes are actually in “promoter” regions. For a gene to be synthesized into a protein a little enzyme has to come over and bind to a spot next to the gene and transcribe the sequence into mRNA.
Other differences are in regions that don’t seem to affect traits at all. There’s a lot of leftover DNA in our genomes from endoviruses, transposons and other events in our evolutionary history. Sometimes the DNA in those regions randomly mutates into something useful and evolution will start acting on it.