My childhood was interesting. Born in 1950 to older parents (Dad was 60 and Mom was 44 when I arrived), I had a sister 12 years my senior and a brother 4 years older than I. There was a brother 5 years older who died at birth. We lived in a small college town of 5000 in Southwestern Wisconsin. Great place to grow up. We never locked our doors. Your parents were either shopkeepers, farmers or worked at the college. My Dad was a shopkeeper (tailor and dry cleaner, raced and trained Harness Horses as a hobby and my Mom did everything else. Talented, she was! We rented out rooms to as many as 10 college students to make ends meet.
I never thought about a sibling being favored over me. We were different kids, different ages, with different interests. The dynamics of our family changed as each one of us arrived as did the circumstances we were born into. When I was 3, my father's health deteriorated dramatically. It meant he was home a lot and I was the beneficiary of more attention from him. My brother and sister were off to school and busy with babysitting, paper routes and mowing lawns for the neighbors. My siblings would joke about "mom liking you best" or that I was spoiled because I was the baby of the family, but it never occurred to me that was true.
We did not have "money" growing up. Compared to today, with so much abundance, having less in a material way was a good thing. It certainly keeps a parent from continually bailing out the kid who is a problem child (even if chronologically an adult) while the "good child" stews about it.
In life, you might get along better with some personality types and that includes your own children, siblings and parents.