We only have one now, but are hoping for another. >And I worry sometimes if deciding to have a single kid is just me being selfish and wanting a family, rather

We only have one now, but are hoping for another. >And I worry sometimes if deciding to have a single kid is just me being selfish and wanting a family, rather than thinking about what would be best for the child (for instance having siblings). I think this is an addressable issue. If you care about your child not being lonely, you could prioritize moving to an area that is family friendly, and/or prioritize making friends with some other families. We moved to an area with lots of parks in walking distance and there's almost always other kids playing there. My son is 4 and an only child right now, but we regularly invite playmates and their parents over for dinner and a playdate for the kids. Almost every weekend my son and some another kid or two will be running around the house in the early evening while I cook some burgers and chat with the parents.