- Health ## Why does blond hair tend to darken with age? Some children have blond hair that darkens as they grow up. What causes this change? When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. - Copy link - Facebook - Reddit - Pinterest - Flipboard If your blond preteen seems to be turning into a brunette, you're not imagining things. For some children, hair that starts out platinum blond gradually becomes darker and may end up dark brown, or even black, as they grow. So what causes this change? The short answer is that hair color is…