Entertainment Tonight's Mark Steines sat down with new parents Charlie Sheen and wife Brooke Mueller Sheen at their home for a new interview airing tonight.

The Sheens open up to ET about the birth of their twin sons, Bob and Max, born 7 weeks premature.

"It was scary," Brooke says. "I went to the NICU to see them and words can't express how amazing and shocking to see two human beings that came out of me. But I was scared. Our babies had so many tubes on them, it was frightening. I didn't have the easiest pregnancy. I had preeclampsia, gestational diabetes and cholestasis." Charlie adds, "She would have been in serious jeopardy had they stayed in longer."

Charlie also sets the record straight on the reported heart problem Max suffers from, "They were 7 weeks early so things were still developing. Max has something called ejection fracture. It's the volume at which the heart pumps and how much blood the heart can pump. There wasn't anything that any other premature child, especially a twin, doesn't normally go through. Things are gradually going toward normal." Charlie goes on to explain the condition that kept baby Max in the NICU longer than brother Bob, "The reason he had to stay longer in the hospital than Bob was a weight issue."

Today the Sheens say the twins are "doing great." "They are completely Sheens," Brooke jokes. "They don't have any Mueller genes. I'm like, 'Can I at least have an ear?!' Bob looks identical to Charlie. Everybody at the NICU called him Charlie. And Max looks like (Charlie's dad) Martin."

Charlie tells ET that his two daughters with Denise Richards, Sam and Lola, love to hold their baby brothers. "I think they think they might be dolls," Brooke says. Charlie jokes that he has a different issue when his older daughter, Cassandra, 24, visits. "With her it's more like, 'Don't get any ideas!' At 43, I'm not ready for that label (of Grandpa)."

Tune in to ET Thursday April 23 and Friday April 24 to see our exclusive new interview!