I was adopted by older parents, in their mid-40s when I was adopted around 2 years old. They were the "youngsters" in their families, so it meant I was exceedingly young compared to my cousins and other relatives.
Fast forward a few decades and my adoptive parents are deceased, and we have lost touch with the few relatives I have. My wife is in a similar situation.
We adopted two older children, 7 and 3 at the time, when I was in my mid 40's. It has been great for us and for the kids, a challenge and an adventure, but the biggest miss is lack of family. We have no grand parents to fall back on, let alone great grand parents. It is incredibly difficult to raise kids without an extended family to help out. We manage, but boy do I envy those who have bigger families to lean into. Not to mention the network of cousins, etc that the kids can relate to.