Now 13-year-old son takes a bath with his father. Is it okay? What's the impact?

Yes, but it will play a very good role, because the child has begun to develop. Some children don't know what people will become when they grow up. With the changes of body organs, they will be confused and even afraid, thinking that they are abnormal and look different from others, so taking a bath with their father will not cause such problems. He naturally understands.