He would likely feel a great sense of discomfort. His identity as a boy is being challenged and he may be ridiculed by his peers if they find out what his mom is doing. This can lead to a lot of self - doubt and low self - esteem. He may start to question his own masculinity and feel ashamed of who he really is. For example, if he is forced to play with dolls when he wants to play with trucks, it can be really distressing for him.
The son could be initially surprised when his mom starts getting muscular. But as he sees her dedication, he may start to feel inspired himself. He might think about how his mom is breaking gender stereotypes and be motivated to pursue his own goals with the same tenacity.
He might feel embarrassed at first. Wearing girl's clothes can be quite different from what he's used to and he may worry about what others will think. But he could also feel curious. It's a new experience and he might be interested in how it feels to be dressed like a girl, like how the clothes fit and move.
Some sons might feel embarrassed, especially if they are in an environment where traditional gender roles are strongly emphasized. On the other hand, if the mom explains the situation well, like it's just for a game or a special event, he may be more accepting and even enjoy the novelty of it. If he has friends around and they react positively, that can also influence how he feels.
On the other hand, the son might try to adapt in a way to please his mom at first. But as time goes on, he will likely start to feel a great internal conflict. He might start to secretly explore his true identity while still pretending to be a girl for his mom. This could lead to a lot of secrecy and emotional turmoil within him as he tries to balance his true self and his mom's expectations.
Some sons may actually enjoy it. They might find it exciting to step out of their comfort zone and explore a different side of fashion. However, others could feel really uncomfortable and even resentful towards their mom for making them do something that they feel is not in line with their gender identity.
He might feel embarrassed. After all, in most societies, boys are taught from a young age that there are boy - specific clothes and girl - specific clothes. Dressing like a girl could make him stand out in a way he doesn't want, especially if his peers start to tease him.
The son might seek support from other family members, like his dad or grandparents. They could help him talk to his mom or provide a safe space for him. He could also find solace in hobbies that allow him to express his true self, such as sports if he feels more masculine - inclined.
One possible reason could be that the mom always wanted a daughter. Maybe she had dreams of doing girly things with a girl like shopping for dresses or having tea parties. Another reason might be that she has some unfulfilled desires from her own childhood related to femininity and is projecting them onto her son.
He might feel embarrassed at first. After all, it's not the typical way he presents himself. But if he's in a comfortable and accepting family environment, he could also find it quite funny.
The son probably feels very confused. He is being forced into a role that goes against his natural sense of self. His identity is being distorted without his consent.