As soon as I watched that thing I googled 'was Nat King Cole gay?'. The answer seems to be no, but I got this on Songfacts:
"This song was written by Eden Ahbez, one of the strangest songwriters of the pre-Hippie era. He was a beatnik poet, but more accurately a proto-Hippie, choosing to wear long hair, a full beard and long, white, flowing garments that promoted a Christ-like appearance. He lived in Griffith Park in Los Angeles and ate fruit, vegetables and nuts. Ahbez was born in Brooklyn in 1908, and he claimed to have been raised in an orphanage and to have crossed the US on foot 8 times before age 35. He moved to Los Angeles in the '40s, lived on 3 dollars a week, and lectured on Hollywood street corners about Oriental mysticism.
"Ahbez implored Nat King Cole's manager to look at his manuscript of "Nature Boy." Cole recognized the Yiddish melody, liked the lyrics and added it to his act. It was well received so Cole decided to record it. One problem: Cole and Capitol Records could not find Ahbez in order to secure the publishing rights. Finally they located Ahbez, camped beneath the first L in the "Hollywood" sign.
"Nat King Cole recorded one other Ahbez song - "Land of Love." Ahbez released his own album in 1960 called Eden's Island. He spent time with Brian Wilson before The Beach Boys recorded Pet Sounds. Ahbez, his wife, Anna, and their son Zoma lived in Griffith Park with their bicycle, sleeping bags and a juicer. With their unusual lifestyle, the family became legendary.
"According to his friend Joe Romersa, Ahbez wanted to correct the last lyric. He decided that "The greatest thing you'll ever learn is to love and be loved in return," was not really what he wanted to say, since to be loved in return is too much of a deal and has nothing to do with love. Ahbez said that the last line should be, "The greatest thing you'll ever learn is to love, just to love, and be loved." (thanks, Garry - Anchorage, AK, for all above)
Paul McCartney told Mojo magazine October 2008 that "since I was a kid I'd always loved the melody and words of that song." He added: "The writer is one of these guys who came and went, a little bit of a hippy in his day. He wrote this rather strange little song when you look at the lyrics - it's rather gay! In a nice way."
"This was the first song Nat King Cole recorded where he was credited as a solo artist. His previous recordings were as the King Cole Trio, where he was the piano player and lead vocalist. On "Nature Boy," he didn't play the piano, which to this point was considered his strong suit. It marked a turning point for Cole, who became known for vocal talents on songs with orchestral arrangements; his next two hits were in this style: "Mona Lisa" and "Too Young." Before Capitol Records signed Frank Sinatra, Cole was their biggest star."
Like it says: 'Rather gay. In a nice way.' The first time I heard that tune was when I was a very little kid. It disturbed me then. Not so much now. But I hold you responsible, for reminding me of it.