"It's fun having babies once again," Russell, 59, the longtime partner of Hudson's mother, Goldie Hawn, tells PEOPLE. "We just really like that. And it's fun to watch them grow. It's fun to see what they're grasping."
But the actor has a confession to make.
"I think secretly we're all hoping for a girl," he says with a laugh.
News broke last week that Hudson, 31, who has 7-year-old son Ryder with ex-husband Chris Robinson, is expecting a child with boyfriend Matthew Bellamy, 32, the British frontman for the rock group Muse.
Russell said Friday night at the 8th Annual Living Legends of Aviation Awards at the Beverly Hilton that Ryder also is looking forward to becoming a big brother again.
Robinson and wife Allison Bridges are parents to year-old daughter Cheyenne. "There's a great relationship between [Ryder and Cheyenne]. [Ryder] was very excited about that. And he's very excited about this too," Russell told PEOPLE.
And Russell says that Bellamy fits in great with the family. "He's really fun. We all enjoy him. We understand what Katie sees in the guy. He's a great guy," he says.
Any wedding talk for the soon-to-be parents?
"No. I haven't heard any of that," says Russell.