This article's claim is partially true! First is important to note that they do not make any robust claim in the article that sugar in early life of kids always causes long-lasting health effects. They say that there is a strong correlation based on data from post WW2 UK civilians. Those who were small children, growing up, as sugar was no longer rationed and more accessible had increased amounts of type 2 diabetes among other problems. The article's title, "Britain’s postwar sugar craze confirms harms of sweet diets in early life" is an exaggeration but not a complete falsehood. The evidence does suggest it.