Nope

>“For 50 years, the author cracked the knuckles of his left hand at least twice a day, leaving those on the right as a control...“there is no apparent relationship between knuckle cracking and the subsequent development of arthritis of the fingers.”

http://www.scientificamerican.com/article/crack-research/

Yeah I know that story. One guy isn't enough to convince my parents though. Has there been any study into it?

Now that's dedication.

"Boutin’s team looked inside the hands of 40 people, ranging from those who never cracked their knuckles to those who had done it 20 times a day for 40 years. When hand injury experts examined them before and after cracking, they found no difference between the two groups, suggesting that knuckle cracking does not put your joints in any immediate danger."

This is what I suspect for a normal, average cracker like myself. I don't do it every 5 minutes like some but maybe 5 or 6 times a day. I am 31 now and have been doing it for at least 20 years now and don't notice any issues with my hands. Maybe in another 20 I will regret it. Then again I think I will regret many other things more in 20 years time ;)