Is Only Child Syndrome Real?

https://www.parents.com/pregnancy/considering-baby/another/only-children/?hid=5e0c61783c3a26fc1db3e981fb2acd3d24744fd8&did=8868611-20230420&utm_source=parents&utm_medium=email&utm_campaign=parents-daily_newsletter&utm_content=042023&lctg=5e0c61783c3a26fc1db3e981fb2acd3d24744fd8