Re: Benefits of DNA history?

The short answer is "perhaps" but I shouldn't bet on it. There may be some 
occasion when it might be useful to be able to perform a DNA analysis 
across generations but the chances are pretty low given the rarity of 
genetic disorders. Also, gene tracing in this way - by linkage - will 
proably all but disappear when the human genome sequence is completed and 
the cost of DNA sequencing drops. One day it will be so low that a clinical 
geneticist will simply order a particular gene to be sequenced to find out 
exactly what form of that gene you have. Then DNA from relatives will be 
irrelevant.

Rather than spend money on storing your DNA for you kids and 
grandchildren..., I'd put it in a bank account paying a decent rate of 
interest. That they will really apreciate - or fight over.