The Only Child
Only children are thought to have personality traits similar to firstborns only much more intense, so expect the firstborn personality traits to be slightly magnified in only children.
Instead of having to adjust to a sibling being introduced into the family, only children get to be the center of their parents' attention for a lifetime. And while a parent's attention can be a wonderful thing, only children are often referred to as lonely-onlies, because without the presence of a sibling and some of the attention off them, they have a tendency to become more self-centered and directed. To offset this they need to exercise their social skills with a strong network of friends and family—particularly children of different ages. Parental awareness and participation are key to raising an only child with all the advantages a child with siblings has.