Are the 4:
Wisdom teeth
Most in our family Are born whole and quickly.
You normally have most of your teeth all at once.
But not us four Who would require a detour.
There are 4 teeth which come at some other unexpected time.
We don't want to interrupt Until the rest is developed.
They only come out AFTER the period of loosing baby-teeth has occurred.
So until then we wait To be put into our complete state.
Just poetic emphasis of the previous.
Then everything will make sense When finished is the sequence.?
There is no further normal activity after the wisdom teeth have established themselves.