In an interview with Entertainment Weekly, the writer of Earth 2 James Robinson explains the change:
"The original version of Alan Scott was an older man, and he had a superpowered son, Obsidian, who was gay. The fact that Scott was young now [thanks to a universe-wide reboot] meant Obsidian no longer existed. I thought it was a shame that DC was losing such a positive gay character. I said, 'Why not make Alan Scott gay?' To Dan DiDio’s credit, when I suggested it to him, there wasn’t a moment’s hesitation."
The superhero was originally introduced in 1940 and fathered two children. He was the character DC co-publisher Dan DiDio teases audiences about earlier this month. In the reboot, Alan Scott has a boyfriend, Sam.
Read the rest of the interview with Robinson here.