Can anyone answer a DNA question?

I was thinking about this and wondered if it was even a legitimate question. The 22 pair of autosomes and one pair of chromosomes attach to the string made of phosphates and sugars. Scientists study the autosomes to look for genetic traits. What about the “string” itself. If the string is made of phosphates and sugars, is it completely uniform, top to bottom? Or is it possible that pair number one for one person is attached to a portion of string made of a phosphate, and pair number one for another person is attached to a portion of string made of a sugar. Would this be a further variable factor in deciding genetic make-up? Is this even a reasonable question? I don’t know enough about it to know if this question has any validity. I basically want to know if the string is exactly the same for everyone or if there is a possibility that the string composition is random. IF it is a valid question, can anyone give me a link to any studies that have been done? I hope this question makes sense to someone who can tell me if I’m barking into the wind.