Same as the odds of every other child that was ever conceived. It's really easy to look backwards in time, think of every single "if this never happened..." moment, and conclude that the probability is near zero. And you would be right.
Did your mom have a daughter? Female answers “yes”
Did her mom have a daughter? Yes
Did her mom have a daughter? Yes
This lineage of course extends beyond even human history back to Proto life forms.
And then you end it with “after all that, you’re ending the legacy by not having a daughter”.