How is it possible that my skin temperature is so constant?
Examine your code closely.  It appears that you are partially implementing extended resolution calculations in this line of code:

  float TemperatureSum = tempRead / 16;


In the DS18S20 specifications the extended resolution equation used is:

 TEMPERATURE = TEMP_READ * 0.25 - ((COUNT_PER_C - COUNT_REMAIN) / (COUNT_PER_C))


Where COUNT_PER_C is a DS18S20 register containing a value of up to 16.  Maybe that is where 16 originated?

I believe what you want to do is divide the recovered value by 2.0 base on table 1 from the DS18S20 specifications:

  float TemperatureSum = tempRead / 2.0;


Don't forget the "." in case the compiler you are using decides to do integer math dripping the "float" part before assigning it to TemperatureSum.