X&X || X&Y
either way the Y is only one in three, in the XX the Y is kicked out but not without taking a copy of the X
The X feels abandoned and tries to get back at(to it may seem) the X mother ship but it will only ever have a temporary port of call
If the XX is no longer a viable progenitor then it may acquire an XY during it's decaying state.
Not so likley that a viuable XY will hook up to an sterile XX for long.