BOSTON — John Korir of Kenya joined his brother as a Boston Marathon champion on Monday.

Six months after winning Chicago, Korir mastered the 26.2 miles from Hopkinton to Boston’s Copley Square in an unofficial 2 hours, 4 minutes, 44 seconds — the second-fastest winning time in race history.

After crossing the line, he was greeted by his older brother, 2012 Boston winner Wesley Korir. Although the race has been won by a pair of unrelated John Kelleys and two different Robert Cheruiyots, the Korirs are the first brothers — or relatives of any kind — to win the world’s oldest and most prestigious annual marathon.

Korir tumbled near the starting line but recovered quickly from the fall and pulled away at the 20-mile mark, building a minute cushion between himself and the rest of the field with two miles to go.

Korir, who appeared to lose his bib in his early fall, pulling it out of his running tights as he sprinted down Boylston Street. He had the paper in his hands as he held his arms out wide to break the tape at the finish.

Conner Mantz of Provo, Utah, finished fourth after losing a three-way sprint to the finish with Alphonce Felix Simbu of Tanzania and Cybrian Kotut of Kenya. Simbu was second and Kotut was third.

The Associated Press and Reuters contributed to this report.