Is Justin Bieber really a baby daddy?

Mariah Yeater says yes, and the Biebs says… well, he’d rather focus on music and not the gossip.

Bieber posted a Twitter response yesterday: “So Im going to ignore the rumors . . . and focus on what is real. an opportunity to help by doing what i love. Judge me on the music! Love yall.”

Jimmy Fallon took a musical approach to the Bieber Baby Mama Drama last night, performing this spoof song “It’s Not My Baby.”

The woman who claims Bieber is the father of her baby hit back at his denials through her lawyers Thursday, and called again for the singer to take a DNA test.

Lance Rogers told Star exclusively, “Mariah Yeater is pursuing a modest and rightful claim. There is credible evidence that Justin Bieber is in fact the father of her baby. The evidence will be revealed in court.”

“She is not seeking exorbitant compensation,” Rogers continued. “She merely requests that Justin Bieber provide a DNA sample to verify that he is the father of Mariah Yeater’s baby, and if so, to help provide child support as required by California law.”

See photos of Mariah Yeater below:

Yeater’s lawyers pointed out that the singer, who is dating 19-year-old pop star Selena Gomez, had not denied the claim.

“It is noteworthy that Justin Bieber himself has not denied the fundamental fact that he had unprotected sex with Mariah Yeater following a concert in Los Angeles,” Rogers and Pare said.

They added, “If Justin Bieber is willing to voluntarily undergo a paternity test Ms. Yeater welcomes such cooperation and will be happy to resolve this issue in a less public manner.”