A childhood belief about appearance

I used to believe that all twins were identical. It’s not that strange a belief, especially that I did find out a long time ago that there are also non-identical twins. But - I have aunts who are twins and I always just presumed they were identical, and then I met my fiancés aunts who are also twins and again I thought they were identical. About 2 weeks ago my sister told me that my aunts are not identical. I was so amazed and so mentioned it to my fiancé and he then mentioned that his aunts are not identical! (He said ‘did it not give it away they look nothing alike?!’) I’m now 27 so spent all those years believing my own aunts who look nothing alike were identical (and about 5 years thinking his aunts were identical)! It goes to show that those childhood beliefs don’t really let go!