Yes, it's very sloppily worded. The "it" does indeed refer to "a cell"; the second sentence is like saying, "except (some particular cell) doesn't (have the sa

Yes, it's very sloppily worded. The "it" does indeed refer to "a cell"; the second sentence is like saying, "except (some particular cell) doesn't (have the same DNA as all the others." If this (kinda silly) format is to be kept, a better headline is, "All the Cells in Your BOdy Have the same DNA. Except They Don't." An even better headline is one that is sans the clickbaity style - just "Cells in the Human Body Don't All Have the Same DNA."