So when we are making a function that is based on some input, it is important to pass the input to the function. 
i.e var oldestLivingFather = function(people) { ... };
your function works, in this case because you use the variable name people in your function AND the sample input is also called people. However, your function should be ready to take ANY input that is formed similarly to the sample input, no matter what it is called.