In an interview that will air tonight, President Obama’s sister spoke to CNN’s Piers Morgan about her brother’s birthplace–and those who have doubts about it.

Obamas Sister Speaks Out About Trump Birther Talk

Speaking of birtherism–the belief that the president was born outside of the United States–Maya Soetoro-Ng says, “I think it’s ridiculous. He was born in Hawaii. There’s a tremendous amount of proof that has already been presented.”

She added: “I think it is time for people to put [birterism] to bed, put it to rest completely.”

What does she think about Trump’s obsession with Obama’s birth certificate? “Well, I think it’s a shame.”

Obamas Sister Speaks Out About Trump Birther Talk

Soetoro-Ng, Obama’s half-sister, has been on the publicity circuit promoting her new book, Ladder to the Moon, which is a picture book that draws on on memories of her mother, Stanley Ann Dunham.

In an interview with the New York Times, Soetoro-Ng said that her and Obama’s mother “would have been proud and excited that [Obama] had this opportunity to make such a lasting impact on the world.”

The president’s half-sister recalls that even as a young boy, Obama had a flare for executive command: “He was always telling people what to do, so the family would joke: ‘Yes, Mr President.’ He took himself a little more seriously than he does now.”

Soetoro-Ng said that their mother would have been proud of Obama. “She wouldn’t have enjoyed the fact that so many burdens laid squarely on his shoulders and would have wanted to give him peace, love, sanctuary and rest. She would have been a mother first.”