The phrase "accident of birth" refers to something that happens by chance or happenstance, rather than being a result of deliberate choice or action. Full definition
What is needed is a message of unity that includes all citizens, in the true sense of the word, regardless of accident of birth. (politics.co.uk)
How dare you think you're better than others, simply based on accident of birth? (religion.blogs.cnn.com)
These are people who are simply seeking refuge from cruelty and suffering they want to make a contribution and, but for accident of birth, it could be any of us. (totalpolitics.com)