My sister, the youngest in the family, believed she was adopted until she was about 16. Because she was the only fair-haired, fair-skinned, blue-eyed person in a family of all dark, my brother and I had easily convinced her that she had different parents than we had.
When I found out she had believed it until 16, I asked her what finally tipped her off? She realized that no one with two small children, the youngest only 1 1/2, would adopt another one, then make up elaborate stories about the pregnancy, delivery, etc.
A childhood belief about family

others believed things like this
- As a small child I believed that the word was "nakeup", finally I found out that it was actually "makeup".— Hannnah P.
- I used to beleive that the moon was where the local fair was.— tah
- When I was younger, I believed that squinting in a storm would make you cross-eyed... forever.Anon
- i used to think that every family had a brother and sister and they married eachother when they got olderAnon
- First I believed that my parents were brother and sister. Then I thought that my dad was also my mums dad. — Rainbow
- I totally believed my siblings when they told me the family was aliens and had a space ship in the garage.— cully