Research

• Brothers have more often been connected with lower educational success in every subject but math (Lawson) (Bergvall)

• girls have been found to receive a better education when they grow up with brothers rather than sisters (Golsteyn)

• Girls have been found to perform better with maternal affection rather than paternal affection and the same with boys and their fathers

Parents tend to be closer with the child of the same gender as them, this makes sense because a mother/daughter relationship seems to have more common interests than a father/daughter relationship, and same with father/son relationships. When kids are growing up, they go through changes, the parent of the same gender knows what they are going through and how to deal with it. 

• Most sisters have rated their relationships with their sisters better than with their brothers by a large margin

• There are usually more role models in same-gender sibling relationships than in mixed-gender

• relationships between 2 sisters are more kind, sympathetic, and emotionally supportive but also more conflictive

• mixed-gendered sibling relationships are usually less conflictual and same-gendered sibling relationships have more noticeable conflict

• Negative relationships between younger kids and their siblings can result in lower self-worth

• Teasing from brothers can cause bad eating habits and body image 

• Even though teasing from brothers is usually negative,  it can also be in a protective way over their siblings

• Girls with more brothers tend to be more masculine and same with boys with more sisters