QUOTE (Makki @ Jul 18 2010, 08:19 AM)

thats a stupid example. you're either natural hardened since birth, or not. of course it's GM approval, but most of the stuff is pretty obivous...some stuff just isn't acquirable during life. one either has an aptitude towards something or not. one can't learn 100% ambidexterity. many qualities are just inherent.
others like Erased could be aquired, if you let's say save a friendly hacker's life. or you're a student and you buy the College Education quality after you finished university. you could probably invest 20 Karma in Homeground after living somewhere for a very long time. and so on
You are talking about a world where someone can randomly grow scales, claws and bone spikes like something out of a drunken bard's nightmares
It's worth nothing you can learn to use both of your hands equally well. Many who have had major damage to one had to, and continue to use both equally well. Same with natural hardening, your skin builds up calluses after repeaded wear and tear so mentally you could as well (just look at those that are jaded to things like tubgirl because they have seen it too much) so building up a natural resistance to biofeedback damage is about the same as building up a resitance to a drug or toxin.
Aptitude can mean they focused on learning how to be far better than they were able to, the karma cost for the advantage could be considered extra hard focus on finding all the little tricks of the trade and researching the most obscure knowledge on the topic (and they would still need to buy that last point too)