First cousins are the children of your parents' siblings. For example, if your mother has a brother, his children are your first cousins. They share a set of grandparents, which makes them part of the same extended family. First cousins typically grow up together, sharing family gatherings and holidays. They often develop close relationships, playing together during childhood and supporting each other as they grow older. This familial bond can create lasting friendships that extend beyond family events, enriching their lives with shared experiences and memories.