I've had arthritis since my mid teens, and our GP told my husband it's normal to have arthritis in your back by your mid-thirties. And you're right, prevention is probably the best route. A lot of people who haven't been affected by carbs (or certain carbs) are either lucky or unlucky depending upon how you look at it. Some of us get fat. Some of us get serious, but maybe not life threatening diseases relatively young. Some of us end up with something more serious. You figuring out that a lowered carb diet is best for health is probably the luckiest route, because hopefully, you've avoided any serious problems.