Adamo did actually say he wasn't gay when he first started playing Marco, but the more popular his character became, he stopped answering the question. Instead, he said if gay people want him to be gay, to them he's gay and if straight people want him to be straight, to them he's straight. But really, he's straight. He just doesn't want to mess with "Marco's popularity" by answering the question now.
--------
There aren't any gay actors (kids) on Degrassi at the moment.