Is it normal for two sons to pose fully nude in a magazine with their dad?

Back in 2004, Brazilian actor Mateus Carrieri posed nude with his soccer player sons Kaike Carrieri and Rafael Carrieri for G Magazine (a gay magazine).
At that time, Mateus was 38 years old and his sons Kaike was 19 and Rafael was just 18, and all three of them are straight.
Most of their nude photos were taken solo and all of them had erections in their photos.
But there were some photos of the father and sons together wherein they're 100% naked with each other smiling, Mateus was in the middle with his arms around both his sons' shoulders, and his sons were standing beside him, Kaike and Rafael had both their erect penises on top of their dad's erection (like they were sword fighting with their dicks) and all three of them were facing the camera laughing.
In another shot, Mateus and Kaike and Rafael had the heads of their erect penises touching each other, and they were smiling at the camera.
In the interview, Mateus was asked how he felt posing nude with his two sons and seeing them naked. He said that he was so proud to see that his teen sons had such a huge and impressive looking erections. Is it ok for some fathers and sons to be this open with each other?