Watch Jessica Simpson's son celebrate his birthday with 'carpool karaoke' sing-along

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/ Source: TODAY
By Embry Roberts

It should come as no surprise that former pop star Jessica Simpson, 36, wants to instill a love of music in her children. And what better way than to start 'em early and practice at every occasion?

Simpson's household celebrated a birthday this week when her son, Ace Knute, turned 4. The family rang in the big day with some good old-fashioned "carpool karaoke" ... and a giant cake, of course!

A video Simpson posted to Instagram featured a duet between the birthday boy himself and his older sister, 5-year-old Maxwell Drew, who graduated from nursery school last month.

"...and he is 4," Simpson captioned the clip, adding emoji of a weeping face and a heart.

As for the kids, they're naturals!

Later, Ace sat down to a birthday cake that was almost as big as he is.

"May wish #4 come true my beautiful baby boy," Simpson wrote. Aww.

As for Simpson, she celebrated seven years with the kids' father, Eric Johnson, in May. Simpson has said that their family is complete, telling Ellen DeGeneres, "We got an IUD. Nothing is going to get into that uterus."

She continued, "I have two beautiful children and I'm not having a third. They're too cute! You can't top that."

We would have to agree on the cuteness!

Happy birthday, Ace!