This is a bit late of a response, but I just have a few things to say. I have a sister only a few years younger than me who is one of my best friends. I don’t think I ever really felt sad to be an older sibling; I loved sharing my life with another person and getting to take care of her. I think it boils down to how well the parents are able to meet the needs of both children simultaneously and make sure that one of them isn’t being neglected, as well as the older child’s temperament.

I want only one child; it wasn’t at all impacted by my relationship with my sister, but because I don’t think I could handle more than one kid for mental health purposes and because I’d prefer to have a life outside of being a full-time parent or something.