Real age of John Wayne in The Shepherd of the Hills
In the movie The Shepherd of the Hills, John Wayne was:
33 years old
That was the real age of the celebrity according to our calculation.
The calculation of the shown age took into account the first day of the year in which the movie The Shepherd of the Hills was released:
January 1, 1941
And the day in which John Wayne was born:May 26, 1907
Since movies usually don't take more than one year to be released since the beginning of the filming process, John Wayne may have been one year younger or one year older than the shown age while some scenes of the movie were being filmed.