The How I Met Your Mother comedian admits he was well aware of his attraction to other boys before he had even reached puberty.
Harris has spoken openly about his sexuality in a candid new TV chat with Oprah Winfrey, and when asked when he first knew he was gay, he replied, "Probably six, seven - young."
The actor even tried to follow in his heterosexual male friends' footsteps and dated a number of women - but each time he knew something wasn't right.
He added, "Good times. I did feel like it wasn't clicking like it was supposed to, and kept wondering, was it me?"
Harris has since found happiness with partner David Burtka and the couple welcomed twins Gideon and Harper via a surrogate mother in 2010.
The full interview airs on Oprah's Next Chapter in America on Sunday (03Jun12).
More News on Hollywood.com