Don't insert inner objects in Entity Framework 5

Question

I have a class:

public class Foo {
    public Guid Id { get; set; }
    public Bar Child { get; set; }
}

When I insert into Foo via context.Foos.Add(myFoo), a Bar is being inserted into the database if it is not null.

How can I prevent this from happening? Do I have to set Child to null prior to inserting into the context?