McKellen, 73, told students at a London school this week his formative years were spent covering up his sexuality, and his performances had to be flawless.
"I think that's why so many great British actors are gay," McKellen said. "We spent so long pretending to be straight, to be someone else, that eventually we became very good at it."
McKellen, who starred in "X-Men" and "Lord of the Rings" has been touring schools around Britain as part of a campaign by the Stonewall charity to combat bullying of homosexual students, Britain's The Daily Telegraph said.
McKellen publicly acknowledged his homosexuality in 1988 and later said it boosted his self esteem and made him realize his public stature could help those "whom society either ignored or abused," the newspaper said.