Who Gives Birth?

We have a movie of our wedding. K really likes to see our wedding movie. She likes to watch her relatives. Someone, though, is missing. O's older brother, E, wasn't married yet. His wife is conspiciously absent from the movie. K asked O where her aunt is. O told her she wasn't around yet. K responded, "Oh, She's in E's belly." All of a sudden, we realized how much information K is still missing - only women give birth, the age difference between a person who gives birth to the one being born, how much time it takes for a person to grow up, the relationship between husband and wife versus mother to child.