I agree with the statement, but with caution. Not all inequality stem from circumstances, as many are due to personal choices or choices made on behalf of the person in question (e.g. family, peers etc.).
Meritocracy don't work on equal terms and this inequality could stem from:
- Financial status. Rich will have the resources to propel themselves to success (or failure due to complacency) as compared to poor (although the poor can achieve equal footing by determination and hardwork).
- Genetic makeup. People are different by genetic makeup. Some people have the capacity to learn at faster rate than others. The disadvantaged need determination and handwork to achieve equal success.
- Family background. Families who emphasize education as prerequisite to live better lives will allow their next gen to achieve better in life as compared to those families that don't care. Families will sacrifice for the sake of their children future. Most to the extent of depriving themselves luxury (e.g. Home remortgage, savings, debts, prudent spending etc.)
- Countries' economy. In developed countries, cheap labours don't come from citizen as the governments tend to emphasize the need for skilled workers, and hence invest on the education system to produce brains rather than muscles.
- Personal choices. Meritocracy waits for no one. People who are determined and willing to put effort and focus will succeed, while those who don't care, get left behind.
- Others, e.g. serendipity, friends, mentors, character (pleasant character attracts right people and friends).