It is challenging to provide a specific reason without knowing more context about your family's beliefs, cultural background, and individual circumstances. However, there are a few common reasons why a parent might express such a rule:
Cultural or Religious Beliefs: Some cultures or religious traditions have specific modesty guidelines, especially regarding dress codes around family members. It could be a part of their cultural or religious practices to encourage modesty within the family.
Age and Privacy: Depending on the age of your brother, your mom might want to maintain a level of privacy and modesty within the family setting. This is more common in families where there is a significant age gap between siblings.
Personal Boundaries: Your mom may feel that setting boundaries about clothing choices helps establish and maintain a sense of respect and appropriate behavior within the family.
Body Positivity and Self-Esteem: Some parents might be concerned about body image issues and self-esteem, especially if one sibling is older or more physically developed than the other. They may want to create an environment that promotes positive body image for all family members.
Family Values: Certain families have specific values or traditions related to dress codes and behavior, which might influence your mom's decision.
Regardless of the reason, it's essential to have open communication with your mom about your feelings and concerns. Try to have an honest and respectful conversation to understand her perspective and express your own feelings. It's possible that your mom might be willing to explain her reasoning or consider your perspective as well.
Remember that every family is unique, and different families have their own rules and customs. What is essential is maintaining healthy communication, empathy, and understanding within the family unit.