BOM Native Type or Primitive Type Object to Business Object Attribute

Assigning a BOM Native Type or Primitive Type object to a Business Object attribute is by value: 

data.car.make = data.bus.make;
data.bus.make = "Ford" // will not affect car.make
 

data.person1.age = data.person2.age;
data.person2.age = data.person2.age + 1;
 
 data.person1.dob = new Date("1968-01-04");
data.person2.dob = data.person1.dob;
data.person2.dob.setFullYear(1970); // person1.dob is now 1970-01-04;