This is something I've thought about before regarding Donkey Kong characters, but I've never really seen it fully addressed in the games or by Nintendo.

Are the Kongs all related? Or is Kong just a name they use as members of a community? I'm hoping it's the latter, otherwise Donkey Kong and Candy Kong have actually been siblings. >.<

Stop, its time to put the keyboard and mouse down.

Go play actual games you sick monster!!!!

*bludgeons you with a baseball bat* I do play actual games. Haven't you noticed you hadn't heard from me in a while?

No, I haven't. And I'd be the first to notice. :(

You're thinking waaaay too much about fictional characters, my friend.

That would explain how they have failed to climb the evolutionary later. You know...like based on how they can talk and act like humans...but remain as primates with an intelligence level lower than an actual human...

I didn't notice that you hadn't noticed...

Then how do you explain their abilities to use vehicles and make fruit guns out of trees?

Because they can only make fruit guns and use vehicles out of trees.  If they were higher up the evolutionary latter, they would use real guns and drive cars made of metal.

Not unless Wrinkly had a habit of going behind Cranky's back.  I mean, there several different species involved here.

Though I guess that could be head canon as for why Cranky became cranky.