I can provide some general information on this topic.
Whether or not a mother showers with her son is a matter of personal and cultural preference. In many cultures, it is common for parents to shower with their young children as a way to bond, teach hygiene habits, and ensure their safety in the water. As children grow older, parents typically encourage them to develop independence and privacy in self-care routines, including bathing.
As children reach a certain age (usually around 4 or 5 years old), it's common for parents to start encouraging more privacy during bathing. This helps children develop a sense of modesty and personal boundaries as they continue to grow and become more self-sufficient.
Ultimately, what is considered appropriate varies between families and cultural norms. It's essential for parents to make decisions based on what they feel is best for their children's well-being and in line with their family's values. If parents have concerns or questions about appropriate boundaries, they can seek advice from pediatricians or child development experts.