Answer:
Middle names are often chosen by parents at the same time as the first name. Popular middle names are identical to those of first names, such as John, James, David, etc., with an emphasis on biblical figures (again, like first names).
In the United States and United Kingdom, a male's middle name is sometimes his father's first or middle name. Alternatively, a male's first name may be the same as his father's, in which case the middle name may be used as if a first name so as to distinguish him from his father. People who are known primarily by their middle name sometimes abbreviate their first name, rather than their middle name, to an initial (e.g. F. Scott Fitzgerald and H. Ross Perot, although Perot later dropped the initial).