How many out of 40 people is a redhead?

1-2% of the worlds population. But If you look at the Demographics, in Scotland about 40% have the red hair gene.

Also, what do you recognize as a redhead? Do ginger, auburn, mahogany, strawberry blonde, titian also count? Your question is impossible to answer as there are too many variables I am afraid.

Best answer if you ask me: Too few!