This random thought or question just entered my mind. In my case, first time i saw my sister was she was like a year or two years old and i never saw her as a baby. I was 2 years old when she was born. I thought my mom ordered her and she arrived from a bus. Then i heard about pregnancy, i just thought girls get pregnant for no reason and dads are just hired by moms to help her. Yep I had some weird imagination.