If Barack Obama senior were Barry’s father then Barry would be called Barack Hussein Obama Jr. But he is not. He calls himself Barack Hussein Obama II. The II appended to the name is for a child who is named after an older man who is not the father.
The most common name suffixes are senior and junior, most frequent in American usage, which are written with a capital first letter ("Jr." and "Sr.") with or without an interceding comma. In England, the abbreviations are "Jnr" and 'Snr', respectively. The term "junior" is correctly used only if a child is given exactly the same first, middle, and last name as his or her parent. When the suffixes are spelled out in full, they are always written with the first letter in lower case. Social name suffixes are far more frequently applied to men than to women (due to the common practice of women taking their husbands' surnames). In French, the designations for a father and son with the same name are père ("father") and fils ("son"). In Portuguese, common designations are Júnior (junior), Filho (son), Neto (grandson), and Sobrinho (nephew). In many other nations, it is considered highly unusual or even inauspicious to give a son the same first name(s) as his father, removing the need for such suffixes. Sons with a different middle name or initial may also be called Junior as a nickname, but unless the names are identical, the Jr. suffix is never used. President William Jefferson "Bill" Clinton was at birth named William Jefferson Blythe III after his late father William Jefferson Blythe, Jr. (who died three months before Bill's birth). However, when teenage Bill changed his last name to "Clinton" for his stepfather Roger Clinton, Sr., his suffix no longer applied.[1]
Alternatively, Jr's are sometimes referred to as "II". However, the original name carrier relative a "II" is named for is generally an uncle, cousin, or ancestor (including grandfather). The suffix "III" is used after either Jr or II and like subsequent numeric suffixes, does not need to happen in one family line. For example, if Randall and Patrick Dudley are brothers and if Randall has a son before Patrick, he will call his son Patrick, II. If Patrick now has a son, his son is Patrick, Jr. As time passes, the III suffix goes to the son of either Patrick Jr or Patrick II, whomever is first to have a son Patrick. This is one way it is possible and correct for a Jr. to father a IV. Another example involves President Ulysses S. Grant and his sons Frederick, Ulysses Jr, and Jesse. When Frederick's son Ulysses was born in 1881, Ulysses Jr did not yet have a son named after himself. Therefore, Frederick's son was Ulysses III. Ulysses Jr's son, born afterwards in 1893, was Ulysses IV. Jesse's son Chapman was the father of Ulysses V, as neither Ulysses III nor Ulysses IV had sons named for themselves.
In practice, it is quite uncommon for families to go beyond "IV" in naming children. However, notable examples of families with members containing the suffix "V" include the Taft family (William Howard), the Vanderbilt family (Cornelius), the Astor family (John Jacob and William Waldorf), the Rockefeller family (John Davison), and the Roosevelt family (Theodore). Former Major League Baseball pitcher Orel Leonard Hershiser IV and singer Usher Raymond IV also have sons with "V" as their suffix.