Maybe she was short on girl models for her sewing projects and thought her son could be a good stand - in.
She might be trying to teach her son about gender fluidity in a very hands - on way. By making him crossdress, she wants him to understand that clothes don't have a fixed gender. It could be part of a broader lesson on acceptance and diversity in her parenting style.
It could be for a cultural or traditional reason. In some cultures, there are certain ceremonies or events where boys might dress as girls or vice versa as part of the celebration. So, the mom is following that cultural norm and involving her son in it.
Well, perhaps the sister is really into fashion and wants to experiment with different looks on someone, and her brother is the most accessible model. Or she could be preparing for a school play or a local theater production where she needs to practice dressing a male as a female character. Maybe she just wants to break the gender norms in a fun and harmless way within the family environment. It could also be that she's trying to teach her brother about empathy towards the opposite gender by making him experience what it's like to be dressed as a girl for a while.
One reason could be that the mom has a very liberal view on gender and she oversteps boundaries in trying to instill that in her child too early. Another might be that she is using the child to fulfill some sort of personal fantasy or wish she has related to having a different - gendered child.
One reason could be for entertainment, like in a family skit or a local theater production. It adds a comical element. For example, if there's a lack of male actors, a mom might crossdress to fill the role and make everyone laugh.
One reason could be for fun. The mom might think it's a humorous and light - hearted way to make prom more interesting for the child.
Misbehavior towards others is also a reason. For example, if the brother and sister are fighting with each other or being mean to their neighbors or friends, the mom may feel the need to discipline them firmly. Also, lying can be a cause. If they are caught in a lie and the mom wants to teach them a lesson about honesty, she might spank them. However, it should be noted that these are traditional reasons and in modern parenting, there are better ways to deal with these issues.
One reason could be for comical purposes. It can create a really funny situation that lightens the mood in the relationship. Just like in the story where the wife crossdresses as her husband to surprise him when he comes home.
Maybe the story is about a family that values creativity and self - expression. The mom might see making her son wear girls' clothes as a form of art or a way for him to explore different identities. Another possibility is that it's part of a plot to show the son's journey of acceptance in a community that has different views on gender.
In a more heartwarming plot, the son might be bullied at school for his unique style. So the mom crossdresses as him to experience a day at his school and understand his situation better. She then uses this experience to help the son gain confidence and stand up to the bullies.
Well, it could be that mom is feeling lonely or her own children are growing up and leaving home. So she wants her sister to have a baby to bring back that sense of family togetherness. It could also be that she sees her sister as a great potential mother and thinks a baby would complete her sister's life. However, these are still mom's own projections and not valid reasons to force the sister into pregnancy.
It could be a misunderstanding. Maybe he was just using it for some art project at school where he needed different fabrics and the panties were just one of them.