Emma and Julia Roberts
Evan Agostini/Getty; Jason Merritt/FilmMagic
06/25/2007 AT 08:20 AM EDT
Raising three young children will be a breeze for Julia Roberts
, her niece, Emma Roberts, says.
"She is really easygoing and loving," the 16-year-old Nancy Drew
star tells PEOPLE. "She's a great mom."
Roberts, 39, and husband Danny Moder, 38, welcomed their third child
, a boy named Henry Daniel Moder, on Monday in Los Angeles.
The couple – who will celebrate their fifth wedding anniversary on the 4th of July – are also parents to twins Hazel and Phinnaeus, who turned 2 in November.
"[They] are really happy," says Emma. "It's a good age difference with the twins."