what happens if i uninstall my sims 3 game will my family and house be deleted

yes if you uninstall with out backuping your stuff you will loose saves ,sims etc

go to the electronicsarts/thesims3 folder if you have saved sims in CAH copy that folder to the desktop will do or a flash/thumb/portable drive

copy the saved sims folder

saved games

recorded videos (if any )

screenshots (if any)

Downloads folder thas your store bought items (inculding free store  items you have gotten)  as you will need to install your downloads again if reinstalling the game that way you won't have to redownload your store items  just open the folder and click the item to reinstall it back into your game once it's reinstalled

edit to add if you wish to save your sims and th ehouse go to edit town save them to the libiary then use the share button to export your sim/house

then in the electronicsarts/thesims3 folder  copy the exports folder then when you reinstall your game you can then open the export folder click on it and install your sims/house and they will be in the libiary to place back ingame andready to play with again