Holy shit, this is one of the dumbest ideas I ever heard of.
First of all, the whole premise is dumb: if children are not "capable", either they or their children will lose all inherited money, therefore in most cases money WILL re-distribute naturally anyway.
Second, as many people have already pointed out here, double taxation is a no-no. How about raising taxes for very rich people instead?
Third, what's the point of working your ass off, if you can't pass anything you earned to your children when you die? This idea is a huge demotivator.