And it’s not necissarily that actors’ heads are bigger than normal so much as it is that they are super skinny to offset the “camera adds 5 lbs” thing that their heads looks so big.
It wasn’t Dolly Parton, it was Merv Griffin. He repeatedly said that people liked big headed actors on television more than people with smaller heads. That’s why giant headed Pat Sajac and and Vanna White got picked to host “Wheel of Fortune”.
Directors had to use lighting tricks and camera angles to disguise the fact that Marlon Brando’s head was 3 or 4 times the size of a normal person’s head.
This is my favorite Dolly Parton quote (which is probably apocryphal):
Dolly was having her handprints and footprints cast into the concrete plaza at Grumman’s Chinese Theatre, which is typical for many celebrities. When a news reporter asks her why she didn’t cast her more famous “appendages” instead, Dolly smiled and replied, “Aw sugar, I didn’t want some small kid to fall in them and get hurt!”