Selena Gomez expecting

Selena Gomez at the premiere of "Monte Carlo". (NYC)

A younger sibling that is! Phew, because Justin Bieber certainly has had his fair share of baby daddy drama.

The "Love You Like a Love Song" singer has been an only child for 19 years, but Gossip Girl reported that's all about to change.

"Momma and Brian are finally letting me share the news....My mommy's carrying my baby brother or sister :) I'm the happiest girl in the world!" she tweeted on Friday.

Looks like someone's going to be spoiled rotten.

According to E! News, Gomez's biological parents divorced when she was only 5 years old. However, in 2006, "momma" Mandy tied the knot to her current husband and the singer's step-dad, Brian Teefey.

And while the Disney darling has years to go before she has her own children, she and boyfriend Justin Bieber have their hands full with their rescue dog, Baylor.

Bieber's previously denied he also adopted Gomez's canine, but who could resist those adorable puppy dog eyes? He'll also probably have a hard time resisting pampering his girlfriend's future sibling.

As for Mariah Yeater's baby daddy allegations, the 17-year-old pop star is taking them in stride, with Gomez right by his side.

Do you think Selena will be a better sister to a boy or a girl?