Yes, but you only have to double a megabyte 30 times to get a terabyte. That's a better perspective to take when dealing with exponential growth. Of course, the genome and the brain are different things, but the point remains that if you believe this will have an exponential growth, being far away from solving it is exactly where you expect us to be right now. And even now, we do have quite good computational models for certain small parts of the brain.