We don't know this.   For some reason Jesus picked male disciples..and the Church respects this decision and action by Jesus..and Jesus wasn't shy about tuning people's understanding and practice on many matters....just think of how he corrected the "divorce" practice.

Not so with the priesthood. He picked males. 

And for 2 thousand years....the Church has continued that tradition....the way the Catholic Church works is that the past always gets of vote on matters such as these.

That creates continunity.