The girls' mum, Courtney Solstad, filmed her daughters' reaction to meeting their brother for the first time and posted the adorable video on Facebook.
"The girls knew nothing about Nathan until this," Solstad wrote.
"We met them at the door and told them that we had been out Christmas shopping and got them a gift to share."
The three young girls walk cluelessly into the room at the beginning of the video and soon spot their baby brother sitting under the Christmas tree.
Two of them instantly clap their hands over their mouths while the third young girl walks in behind them and is the last to see her brother.
It's not long before one of the sisters begins jumping up and down in sheer excitement and waving her hands in the air.
"He is so, so sweet," says one.
"Can I touch him?" adds another.
The video doesn't show their new baby brother, but sees the girls kneel down and reach over to him wanting to hold him.
It ends with the girls talking to their brother through their happy tears: "Hi little Nathan, hi!"