Is it normal to pose naked for a magazine with your father?

In 2004, Brazilian actor Mateus Carrieri posed nude with his soccer player son Kaike Carrieri for G Magazine (a gay magazine).
At that time, Mateus was 38 years old and his son Kaike was 18, and both of them are straight.
Most of their nude photos were taken solo, but they have one photo together wherein they're 100% naked with each other smiling, Kaike had his erect penis on top of his dad's erection (like they were sword fighting with their dicks) and both were facing the camera laughing.
In another shot, Mateus and Kaike had the heads of their erect penises touching each other, and both boys were smiling at the camera.
In the interview, Mateus even said that he was so proud to see that his teen son had such a huge and impressive looking erection.