5.9Predominant family

In C major, the strongest common predominant chords are:

ii = Dm

and

IV = F

Compare:

F → G7 → C

with:

Dm → G7 → C

Both sound natural.

Dm:

D F A

F:

F A C

They share:

F and A

That helps explain why ii and IV are closely related in function.

So:

Predominant family: ii, IV