Which Assassin's Creed game first introduced the Kenway family as a central storyline?

Assassin's Creed III first introduced the Kenway family as a central storyline.

The game follows Ratonhnhaké:ton, also known as Connor, during the American Revolution. Connor is the son of Haytham Kenway, who appears as a playable protagonist during the opening portion of the campaign, making the Kenway family central to the game's structure.

The family storyline continues in Assassin's Creed IV: Black Flag, which stars Edward Kenway, Haytham's father and Connor's grandfather. Assassin's Creed Rogue also connects to the same family through Haytham and other recurring characters.

Assassin's Creed III was released in 2012. Its historical settings include colonial Boston, New York, and the American frontier. The title can be confused with Black Flag because Black Flag focuses more heavily on Edward, but the Kenway family narrative begins as a major playable thread in Assassin's Creed III.