I'm not an expert, but I would assume X would have a genetic mutation that branches off of the lineage of X-1 and continues on, now technically being "human".

I'm not an expert, but I would assume X would have a genetic mutation that branches off of the lineage of X-1 and continues on, now technically being "human". Obviously this isn't a single person, but rather an estimate for the time period where this branching occurred. Or something like that. How close am I?