We need a whole lot more information than a picture can provide. http://forum.grasscity.com/sick-plants-problems/226015-when-posting-your-sick-plants-questions.html
I'm starting to think that I took colones from the wrong mother. This is a clone off a plant I took from a mother I planted from seed. The grow conditions for the mother were not to great. And it got burned by the lights. Cfl's. The mother plant is now budding and is not doing that great either. Some of the clones appear healthy but a couple of them are having problems like this. I have another plant from the same seeds that is doing great. I induced flowering and have been using full line fox farm nutes. I'm pretty sure this plant has had two doses of Open Sesame pretty sure I gave this one half strength the first time and Tiger bloom maybe some big bloom too. I'm kinda disorganized right now.
If you don't know what you've been giving them there's no way you're gonna be able to pin down the problem. I can assure you it isn't the problems with the mother unless it's genetics. I doubt it is a genetic issue... it sounds like you just slipped up from not keeping track of what you're giving them.