+1. Also, we don't have many data points to suggest that this is relatively rare that objects from outer solar systems tend to move in later. May be that is qui

+1. Also, we don't have many data points to suggest that this is relatively rare that objects from outer solar systems tend to move in later. May be that is quite common, we don't really know - we don't have enough data. And even if we assume it is rare, how rare exactly? The numbers are so uncertain that we can say nothing yet.