This kind of "imposter syndrome" in software development is for me rather foreign. I've never been born with a silver spoon and I've seen lots of people who are math and programming geniuses but I've worked very hard at learning development and know how to do a good job now. I find it waste of energy to philosophise on whether one is good or not. To my ears it sounds almost like humble brag. Or a question from a girlfriend "am I ugly?" where the correct answer is not yes... :)