I am the second of four children, and all of us are college graduates. My older brother by four years is a typical firstborn—straight A's, college grad, M.D., 2 high-achieving daughters. Though I've never actually asked him, I am sure he is the highest in both annual income and net worth. His wife is in the upper echelons of a large non-profit and I am sure is nothing to sneeze at either in the earnings department. I think she is also a firstborn. They might well be able to buy the other three of us lock, stock and barrel.
I'm not sure which of the other three of us comes next, and it's an apples to oranges comparison anyway. My sister (not quite a year younger than I am) married, had two daughters, then was divorced/single mom for more than ten years, and has recently remarried, acquiring two teenaged step-children in the process. One of her daughters is a college grad and teaches elementary school. The other is studying nursing (following in Mom's footsteps). Our other brother, the youngest of us four, has had serious health challenges the last several years which I'm sure have drastically affected his finances and future job outlook. His wife is a college professor (also a firstborn), and they have three daughters, one currently in college, one in high school and one in elementary school.
I'm pretty sure that both my sister's and younger brother's household annual income is higher than mine, but I have never married and have no children, so I've probably been able to save a larger proportion of my income than any of my siblings. It wouldn't surprise me if I am putting more money into retirement savings than either my sister or my younger brother. My-brother-the-doctor is probably ahead of me on actual dollars, if not by percentage. OTOH it also wouldn't surprise me if they are all wondering why I took me so long to get a clue, because I've only been saving at that level for two years.