The research I mentioned reported aggregate results, of course, not a universal outcome. One can think of many reasons for that result, unrelated to the particular skills of parents. For example, a father with custody of children is likely to have a higher income than a woman in the same situation.
Congratulations on your sons! I have four boys so far (11 and under), and I'm always encouraged by examples of young men who have turned out well.
I too have four children eleven and under, boy 11, girl 9, boy 8, and boy almost 1. So today that is a big family. But if I were younger and could get started earlier I would go for a large family by old-time standards. I don't mean huge like 10 or 12 buy big like say seven children. My grandparents had seven and were sorta poor and all seven were great successes. All the grandchildren grew up in smaller families and were much less successful and upwardly mobile.
What earmarks American children is being spoiled compared with children in places like Bolivia and Mongolia.
Wish you the best with yours. I too have four sons 12 and under (three from my late wife and one with my current one).