"I was very excited -- another baby in our family. And when she told me that our child might have Down syndrome, I asked myself, I just, I said, 'Why not us? Our family is never one to have that, you know ...want anybody to feel sorry for us,'' he said. "I knew that our family was strong and would be able to handle whatever was thrown at us."
Todd, 45, a former snowmobile champion who worked on the oil fields of Alaska's North Slope, said that Trig will be able to keep up with his family's outdoorsy lifestyle.
"He'll be able to do everything that our -- that all of our other children have done with us," Todd said. "We treat him just as another kid in the house and I look forward to getting him out on the trail this winter."
So, what's the biggest misconception about children with Down syndrome?
"They are just beautiful gifts from God for all of us to learn from ... and to make us stronger as we live," Todd Palin said. "He is just another kid in our house. ... But he has, but he has just been a blast."
Given medical advances and much-improved educational approaches, Trig should grow into a productive member of society.
"At the turn of the last century a child like Trig would have been lucky to perhaps even to make it to 10 years of age," said Gross. "You could easily say 60 years of age now."
Walters also asked Palin if she wants to add more children to the brood.
"I'll stick with the grandkids thing now, but even that can wait another ten years, as Bristol would tell you," Palin joked. "Ten years from now? Oh gosh, bring on the grandkids. I can't wait."
At age 17, Bristol Palin surprised the nation when her pregnancy was announced in September 2008. Bristol gave birth to Tripp Easton Mitchell in December. Bristol and Tripp's father, 19-year-old Levi Johnston, called off their engagement soon after their son was born.
Since then, the relationship between Johnston and Palin has become severely strained, escalating into a full-blown war of words in the media. Johnston accused Palin of being a neglectful and insensitive mother and claimed she called Trig "the retarded baby," among other jabs.
"That's heartbreaking to know that he would say such a thing ... and that's not true," Palin told Walters.
Johnston has also alleged that the Palins are on the verge of divorce -- accusations that Palin denied to Walters.
"Todd and I have been together -- he was 16, I was 17 -- for many, many years. We've been married many, many happy years, and we remain a solid, happy, blessed couple," she said.
Johnston has claimed that he will sue for joint custody of their 11-month-old son -- a move that Palin said she would applaud.
"Well, it will be nice to see, in -- I guess -- even in legal proceedings, a desire to be a part of the baby's life," she said. "That's a good sign."
Johnston has said that Palin was wise not to speak ill of him in her best-selling memoir, "Going Rogue: An American Life," because, "she knows what I got on her."
"He doesn't have anything on me," Palin told Walters.
Johnston has catapulted himself into the media spotlight, posing for Playgirl magazine last week and making public appearances. When asked if Johnston had contributed any of his profits to child support, Palin demurred.