I was not aware of a homophobic past or present in regards to Mark Walhberg. Though it wouldn't surprise me if you were talking about his brother. What events or circumstances brought this to your attention Stowe?
The Wahlbergs grew up in the overwhelmingly Irish Catholic working class South Boston area of Dorchester. Not an oasis of progressive attitudes towards gay in the 50's, 60's and 70's. I don't think Donnie or Mark were enlightened. But I have the impression that Donnie has become more so since being married to Jenny McCarthy. Regarding Mark this was a number of years ago I read in a gay online site that Mark was a homophobe and had used disparaging words about gays. Then in the first season of the show. "Wahlburgers", he was interviewed by one of the entertainment shows and when talking about his family he said that his kids went to Catholic schools so they could be imbued with Catholic family moral values. (That is code used by those celebrities who want to avoid saying negative things about gays - used a lot during our long fight for marriage equality.)
From what I remember from his days with the Funky Bunch he would drop tou down to his famous underwear poses on stage at the end of each concert. And the whole audience of men and women would be whooping, clapping and hollering in approval. His well known gay fan base at the time was partly to credit for catapulting to the fame and fortune which he enjoys today.
He wouldn't be the first or only famous person who is homophobic who doesn't mind taking our money and adulation in furtherance of their careers. Gloria Gaynor is the most recent who comes to mind.