A.J. McLean's daughter loves singing his song 'Sex'.

AJ McLean

AJ McLean

The 38-year-old singer finds it "awkward" that three-year-old Ava - who he has with wife Rochelle - knows every word to the raunchy track, even if she doesn't understand its meaning.

He said: "What's really uncomfortable is her favourite song off of my new album is a song called 'Sex'.

"She doesn't know that's what it's called, but she knows the words. She just sings along. I'm like 'Oh God. Don't. That's so weird! It's awkward. You're making it awkward!' "

The Backstreet Boys singer and his wife are keen to have a second child but Ava is making it difficult for them to find the opportunity.

A.J. told People magazine: "[Ava] just moved to her big girl bed about a month and a half ago.

"She now knows how to get out of her big girl bed in the middle of the night, [knocks on the door], 'Mommy, Daddy?' So Mommy and Daddy are trying to figure out when we get Mommy, Daddy time. We are talking about [baby] number two so it's trying to figure out when and where!"

But the couple are also considering adoption.

He said: "We also talked about adoption possibly as well, to give a child a home. We're in the process of figuring this out. We've given ourselves March 30th [as] our deadline to go one way or the other."