King George V was the first monarch of the House of Windsor
King George V and his wife Mary of Teck had six children together between 1894 and 1905. One of their children didn't survive into adulthood. Prince John, the baby of the family, had severe epilepsy and a learning disability. He died in 1919 at the age of 13.
Their eldest son, King Edward VIII, inherited the throne upon his father's death in 1936. Had he remained king, Edward VIII's hypothetical descendants would have inherited the British Crown.
But Edward VIII abdicated in 1937 in order to marry American divorcee Wallis Simpson. The controversial couple — who were rumored to harbor Nazi sympathies — never had children.
King George VI's descendants dominate the current line of succession
After his older brother's abdication, King George VI took to the throne for a reign of nearly 15 years. He and his wife Queen Elizabeth had two daughters, Queen Elizabeth II and Princess Margaret.
George VI's descendants are set to continue to inherit the throne in the foreseeable future. His eldest daughter Queen Elizabeth II is the longest reigning British monarch in history. Her son Charles, Prince of Wales, is reportedly set to succeed her when she turns 95 in 2021.
The Lascelles family is descended from King George V's only daughter
Mary, Princess Royal, was George V's only daughter.
She had two sons with her husband, Henry Lascelles, 6th Earl of Harewood. The princess's sons went on to produce six grandchildren, 17 great grandchildren, and nine great great grandchildren. The Earldom of Harewood is still held within the Lascelles family.
The eldest two children of David Lascelles, the current 8th Earl of Harewood, were born before Lascelles married his first wife. They were therefore unable to inherit his title.
Leo Cyrus Anthony Lascelles, the only son of Alexander Lascelles, Viscount Lascelles, is also not eligible to inherit his family's royal title, as his parents were not married at the time of his birth.
The dukedom of Gloucester is still held by the descendants of Prince Henry
Prince Henry, Duke of Gloucester, and his wife, Lady Alice Montagu Douglas Scott, had two sons together. One, the Prince William of Gloucester, died in a 1972 plane crash. He hadn't had any children, so the title passed onto his younger brother Richard.
Prince Richard, Duke of Gloucester, inherited his father's dukedom and went on to have three children and six grandchildren.
Prince George's great grandson is set to eventually become the Duke of Kent — but he will never inherit the throne
Prince George, Duke of Kent, and his wife, Princess Marina of Greece and Denmark, had three children before he was killed in a 1942 military airplane crash.
Today, he counts seven grandchildren and 16 great grandchildren among his descendants.
Edward Windsor, Lord Downpatrick, and Lady Marina Charlotte Windsor are both confirmed Roman Catholics, meaning they are banned from succession to the Crown.
However, Downpatrick is still in line to inherit the Dukedom of Kent. He will potentially become the first Catholic Duke of Kent in centuries.