When I was little, our family had pets, a dog and a cat. The dog was male, the cat was female. They looked very different, the cat was small and white, the dog was a big black labrador.
Despite them looking different. I assumed they were the same species. A cat being the female version of a dog, and vice versa.
Once I got a bit older I realised my mistake. It seems a reasonable mistake to make given the circumstances, and the fact I hadn’t known any other pets at the time. But if I mention it to anyone now, they think I’m an idiot!
There was one person who understood where I was coming from. He told me he thought a moth was a male butterfly, and a butterfly was a female moth. Ha! What an idiot!