Danny DeVito and "Twins" costar Arnold Schwarzenegger ... and now we're grandparents together, and we just had a baby. My middle daughter [Grace] had a baby, Sinclair. She's going to be a year ...

Danny DeVito is "busting" with joy ever since he ... "In two years, my daughters have had a baby each, and since these babies have been born, you gotta tamper me down in the joy department.

Danny DeVito and Rhea Perlman have three kids together: Lucy, Gracie and Jake Katie Mannion is a contributing writer at PEOPLE. She has been working at PEOPLE since 2022. Her work has previously ...