If you click on the cell phone in one of your (Young adult or older) sims then there will be an option to adopt a child. If you click on that your sim will make the call and you wil get a message somewhere along the lines of "Thank you for adopting, a social worker will come soon with your new member!" Once the member comes a pop-up screen will come on where you select the new child's age and name, (the traits are random)
You need the Pets expansion pack in order to adopt a pet. It is fairly the same as the child, except that you get to see what the animal will look like before hand.
