Or current DK's son or something. Diddy Kong was originally supposed to be a redesigned DK Jr., anyway.
I kinda like the theory more that DK was rampaging in Big Ape City, and someone in the city, perhaps an investor or something, locked DK up and shipped him off to a jungle island where the big ape could live in peace without causing a ruckus in the city. I like the idea that it was K. Rool who took over the city and had DK sent away, then some time later they stole the bananas from the island hoping the Kongs would starve to death. When that failed, he returned to Big Ape City and DK followed him and overthrew his reign of terror.
Of course, that's just me, go-to story guy. I love a good story, and coming up with ways on how games, even non-story based games, all tie in together. I far prefer the notion that DK is a reformed villain than the son/grandson of a retired villain, though...