You will notice a section on your character sheet called Birth Skill. This is what one or both of your parents did for a living, and you absorbed a certain amount of this knowledge or skill by growing up around it, enough to give you a general idea of things. This isn't as powerful as a non-weapon proficiency, but will give you a chance to know more than other people about this subject, though it generally doesn't give enough to be able to make something, you may be able to identify a thing, or know some facts about a subject, person, place, or the like.