Why Does Hair Often Darken with Age?Bruce Lee once famously remarked that his son Brandon was the only blonde Chinese in the world.Although when Brandon grew up his hair became as black as the ace of spades.The majority of blonde babies do not become blonde adults,just as the many babies with blue eyes that later change to brown or green.Genes, like light switches,can be turned on and off and the color of our hair and eyes can change over time when the respective genes are turned off.Genes are a complicated issue,so complicated in fact,that even scientists do not yet fully understand them.The color of our hair is irrefutably determined by our parents and because of the innumerable random possibilities at play at the moment of conception,it is rare that siblings are ever exactly the same and explains why many hair color dissimilar families existuntil the children arrive at an age when they are old enough to reach for a bottle of bleach.