Ronaldo named his son Cristiano.
Ronaldo's baby was born in the USA on June 17 to an American woman, widely reported to be a surrogate mother.
The 25-year-old is currently on holiday in the Algarve with Russian girlfriend Irina Shayk, and Ronaldo's sister Katia is looking after Cristiano Jr.
"The baby is doing very well," Katia said.
"We are looking after him while Cristiano is away. He's called Cristiano just like his dad. Cristiano chose the name but we like it."
Katia also played down the fact that her brother had chosen to become a single dad.
"Some people may think it's strange, but we don't," she said.
"We're very happy about what Cristiano has done."
Ronaldo's baby was born in the USA on June 17 to an American woman, widely reported to be a surrogate mother.
The 25-year-old is currently on holiday in the Algarve with Russian girlfriend Irina Shayk, and Ronaldo's sister Katia is looking after Cristiano Jr.
"The baby is doing very well," Katia said.
"We are looking after him while Cristiano is away. He's called Cristiano just like his dad. Cristiano chose the name but we like it."
Katia also played down the fact that her brother had chosen to become a single dad.
"Some people may think it's strange, but we don't," she said.
"We're very happy about what Cristiano has done."
