Its basically true that your fat cell count remains steady after childhood. When you gain weight they swell up, when you lose weight they shrink. As far as the predisposition to obesity part, I don't think any of the studies have shown a direct correlation.

Here is a good article on the topic: http://www.nytimes.com/2008/05/04/he...-fat.html?_r=1

This is the part that I found really interesting, the fact that fat cells were regenerated even after surgery:
"Obese people who had weight loss surgery had as many fat cells two years after the surgery as before it, even though they were much thinner."