Bobbi Kristina's relationship with adopted brother annoys her grandmother

 Gospel singer Cissy Houston, mother of the late Whitney Houston, reportedly is dismayed that her granddaughter Bobbi Kristina Brown is romantically involved with Nick Gordon, whom her daughter took in as a child and raised.

The Houston family matriarch lamented to a friend that while Brown, 19, and Gordon, 22, are not blood relations, she considers a romance between them "incestuous" and wants him out of Whitney Houston's home.

The celebrity-news site also ran a photo of Brown strolling with Gordon and wearing a large ring, which has spawned speculation of a possible engagement.

Whitney Houston's brother, Michael, told ABC News that Gordon was "like a son" to her. The late singer invited him to live with her over a decade ago, TMZ said, after his biological mother could no longer care for him.

Gordon, whom ABC described as a tech-company partner who still lives in Houston's house outside Atlanta, hinted at the relationship in a Twitter post: "We're just close -- just going through her mom's passing and grieving together.

"Yea we got a little closer and what!!!" he wrote. Gordon then urged "All the haters that don't know us" or the real story to unfollow him on Twitter.

In her recent interview with Oprah Winfrey, Brown did not address her relationship with Gordon. However, msnbc.com reported she has been retweeting support sent to her on Twitter, including this comment: "If people don't understand that's their problem. Do what makes you happy."