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One of the events that led to the War(s) of the Roses was the birth of a son, Edward, Prince of Wales, to (Lancastrian) King Henry VI, and his Queen, Margaret of Anjou, in 1453.
Prior to that time, Richard, Duke of York (a cousin) had been next in line to the throne, and therefore had no incentive to fight. The birth of Henry's son "disinherited" him. Which is why he rebelled in 1455 and helped start the War of the Roses. The events referred to by the Honorable Rose occurred in 1460, during the war itself, but had no bearing on the cause.