If it doesn't hurt when you do body weight squats with zero weight, then you can make it not hurt when you do heavier weights. The trick is to start with body weight squats, or an empty bar, and build slowly. At every step, keeping proper form. Adding only 5 lbs each workout. So many people make the exact claim you're making, without actually going through the painstaking process of starting from no weight on the bar and moving up over a period of a year. You may actually have a real problem in your knees, but if you can do body weight squats without pain, you can work up from there. If you can sit down in a chair without your hands, you can probably work up from there too.