Singer Justin Bieber reportedly wants to start a family with on and off girlfriend Selena Gomez.

The 20-year-old 'Baby' hitmaker has been dating the 22-year-old pop star for four years, and he reportedly wouldn't be upset if she got pregnant soon, reports femalefirst.co.uk.

"They have a very romaticised and immature idea of what it means to have a child. When they first fell in love, they promised each other that they'd be parents one day, and Justin still says he wants Selena to be the mother of his children, especially when he wants to make her happy," said a source. "They're rolling the dice, because they think whatever happens is god's will," added the source.