HOLLYWOOD’s hottest brothers, Mark and Don­nie Wahlberg, are locking horns over Don­nie’s red-hot romance with blonde bombshell Jenny McCarthy.

As the relationship be­tween the former New Kids on the Block pop group member and the newly appointed “View” co-host heats up, a source says Mark – a reformed bad boy who’s now a de­vout Catholic and devoted family man – is trying to convince his older brother that Jenny’s nothing but bad news.

The outspoken TV per­sonality is well-known for posing nude for “Playboy,” using obscene language and writing books about sex. She even penned a best-seller questioning Ca­tholicism.

“When Mark learned Donnie was spending time with Jenny he quickly dismissed it as a fling,” ex­plained the source. “But now that they’re spending a lot of time together and seriously dating, Mark has let Donnie know that he doesn’t approve of the relationship.”

Sparks flew between Donnie, 44, and Jenny, 40, in late March when the “Blue Bloods” star made an innuendo-filled appear­ance on her racy VH1 talk show.

Since then, their rela­tionship has apparently been getting more serious by the day.

But Mark, 42, is trying to convince Donnie that sexpot Jenny isn’t the type of woman he should settle down with.

Mark had his share of trouble as a teen, including numerous ar­rests, drug addiction, vandalism and fighting. He even faced an attempted murder charge when he was 16 after he severely beat two Vietnamese men and served prison time for it.

But Mark has since turned his life around and attends Mass regu­larly. He married his longtime love, model Rhea Durham, in 2009 and the couple have four kids together.

“Mark has settled down and become a family man, and he’s constantly nagging happy-go-lucky Donnie to do the same,” added the source.

“But Donnie couldn’t be happier with his life, especially now that Jenny is in it. And he has no inten­tion of changing the way he lives just because Mark doesn’t like it.

“He’s fed up with listening to Mark preach about what a bad influence Jenny is. Now whenever Mark starts in, Donnie reminds him that he’s made a fortune on the big screen playing roles like a drug dealer or a porn star, so he’s in no position to judge anyone.”