Newlyweds Bobbi Kristina and Nick Gordon slam critics of their 'brother and sister' romance.

Whitney Houston's daughter Bobbi Kristina and Nick Gordon have spoken out for the first time about the criticism surrounding their recent marriage, saying the row has made their relationship stronger.

The couple, who the singer brought up as brother and sister for 12 years before her death in 2012, spoke to set the record straight about their romance.

Bobbi, 20, is Whitney's daughter by singer Bobby Brown, but Nick, 24, was brought into the family as a 12-year-old and was never officially adopted.  

Now they are hitting back against criticism of their 'brother and sister' romance  

Nick told Extra the criticism of their marriage, 'put a fire in us,' to which Bobbi added, 'It lit a fire up under our ass and we went hauling.'

Nick explained, 'The critics can say whatever they want to say… it's like we have a force field and that s***'s just bouncing off of it.'

The couple posed for photgraphers the day after they tied the knot, as critics began to question their relationship because Whitney brought up Nick as a son with her daughter, Bobbi

Nick said: 'Me calling [Whitney] mom, this where everybody gets the…” Bobbi injected, 'Brother and sister…' Nick added, “We were young. Krissy looked at me as an older brother, and I looked at her as a little sister.'

Nick continued, 'She [Whitney] just treated me like she gave birth to me. She treated me like a son. Excuse me for saying this… she treated me better than my birth mother. I owe everything to her.'

Their romance blossomed after Whitney's death at the tragically young age of 49 but the couple said that it was something she would have wanted.

'She made me promise several times to look after Krissy,' Nick said. 'And, Mom, I will never ever, ever break that promise.' 

Very close: Nick and Bobbi at the New York premiere of their short-lived reality show, The Houstons: On Our Own,' for Lifetime in 2012

Bobbi agreed: 'She wanted this. This is something she wanted to see.'

The two also knocked down rumours that Whitney's mother Cissy Houston disapproves of their marriage, which they announced on Twitter on January 9.

Bobbi Kristina stated, 'She told both of us that she loved us very, very, very much, and Nick came up and he said "Grandma, I want to marry her. Is it okay? I need your blessing to do this, if I don’t have your blessing I won’t feel right," and she looked at him and she smiled. 

'She smiled very wide and said, "Yes, son, you have my blessing.” '