Many adolescents opt for a slice of pizza instead of an apple. Why? This dissertation offers unique insights into this question by following adolescents themselves, their mothers, and their best friends over the first years of high school. It was revealed that the food intake of mothers, and less that of best friends, was associated with the development of adolescents’ (un)healthy food intake. For example, the results showed that when mothers snacked more unhealthily, adolescents themselves snacked more later on. The importance of mothers was also demonstrated during the coronacrisis. For instance, it was found that while, on average, adolescents’ fruit and vegetable intake had permanently decreased after the first corona-lockdown, this decrease was not permanent for adolescents whose mothers consumed more fruits and vegetables. Their fruit and vegetable intake returned to pre-pandemic levels. In summary, the apple does not seem to fall that far from the tree.