They are the grandsons of Dr. Cooley, one of the most famous heart surgeons in history, and Peter Kaldis and Charlie Fraser are medical students at UT Health Medical School.
"He's brilliant, he's very witty and he's very fun to be around," said Fraser.
Kaldis remembered how his grandfather's name would often come up in class.
"The surgeon would ask for the 'my scissors' and they'd go in and do a story about these scissors. These are called 'my scissors' because Dr. Cooley would ask for 'my scissors' and he designed these not knowing that I was his grandson," said Kaldis.
And when other med students would find out who they were.
"Most of them say it's pretty cool," said Fraser.
"I remember being little and looking in the Guinness Book of World Records and seeing there's my grandfather's name!" said granddaughter Laura Fraser.
Of the five Cooley children and 16 grandchildren, nine are in the medical field. His daughter, Dr. Weezie Davis, is an ophthalmologist and Peter's mother.
"I'd love to watch him operate, although I would get a little faint and I'd have to sit down from time to time. But he encouraged me, if he hadn't encouraged me to go to medical school I probably wouldn't had enough courage to do it," said Dr. Davis.
Dr. Cooley is a medical legend. He performed the first heart transplant in the U.S. in 1968. And the world's first total artificial heart surgery a year later.
"It brings back some real memories of those exciting days when cardiac transplantation was so unusual and had been done at only a few centers in the world," said Dr. Cooley.
Helen Cooley Fraser, Charlie's mother, remembers looking for something to take for "show and tell."
"I'm going to go into Daddy's study and find something really neat and I took the first artificial heart, which is now in the Smithsonian Institute, to show and tell at River Oaks Elementary," said Helen Cooley Fraser.
"What I don't think people realize is at the core of him he's just a regular fun guy, enjoyable, and pleasant to be around. And that made it easier for me to marry his daughter, I'll tell you that!" said Dr. Charles Fraser, who is a heart surgeon and Charlie's father..
"Nothing gives me more pleasure today than to have somebody 50 years old come up to me and say, 'Dr. Cooley, you saved my life,'" said Dr. Cooley.
He saved Marvin Odum, who spent four months on a ventilator. Other doctors said he wouldn't survive. But not Dr. Cooley.
"His presence, his attitude and his love was certainly a big factor in pulling me through," Odum said.
"I just wrote a memoir entitled '100,000 Hearts' and that's how many heart operations my associates and I had done when I finally stopped operating myself," Dr. Cooley said.
He was 87 when he stopped operating, but continues working as Surgeon in Chief at Texas Heart Institute, which he founded 50 years ago.
"I don't think there are many 92 year olds who are in their office right now like he is," said Charlie Fraser. "And it's because he truly loves what he does."
Dr. Cooley says his legacy is the hundreds of heart surgeons he trained, like Dr. Bud Frazier.
"Our institution is the length and shadow of Dr. Cooley. And I'm proud to be a part of that," Dr. Frazier said.
On Friday night, Dr. Cooley and his daughter passed the torch to his grandson, Dr. Peter Kaldis.
Dr. Kaldis will begin his residency at UT Health in pediatrics and family medicine. His cousin Charlie Fraser is about to begin his second year of medical school.