One of the most positive ways a brother can affect his siblings is by being a positive role model. Setting a good example for his brothers and sisters to follow can help younger sibs better navigate social decisions, according to Kramer in the article "Siblings Play Formative, Influential Role as 'Agents of Socialization'" on the University of Illinois website. The effects from a good role model may include improved performances in school, work and in making good family or relationship choices. An older brother acting as a positive role model can influence his sibling's academic outcomes, as studies have shown. Older siblings who reported high levels of academic engagement positively influenced their younger siblings' school adjustment, according to the study "Longitudinal Links Between Older Siblings' Academic Adjustment During Early Adolescence" in the "Journal of Educational Psychology."

Although friends may change over time, a good brother is there for the long haul, according to counselor Raychelle Cassada Lohmann on the Psychology Today website. Family members have a unique, special bond with each other that differs from the bonds that friends have, typically also having a deeper knowledge of each other. This deeper knowledge is gained from years of living together as well as having this shared history. A brother can offer the same type of companionship that a friend can, but he isn't as likely to move on to a new social situation, whereas a friend might. As a child grows into middle childhood and adolescence, having a positive relationship with his older brother has been shown to increase the likelihood that the younger sibling will have healthy feelings of self-worth and fewer signs of depression.

Honesty is an essential part of any healthy relationship. This trait is particularly important among family members and siblings. A good brother should maintain an open, honest way of treating his siblings. This doesn't mean that he should relay the brutal truth. Telling the truth without tact can hurt a sibling's feelings and cause distress. For example, saying that your brother's girlfriend left him because he is unattractive and dresses poorly is likely to cause conflict. On the other hand, telling your brother that he could update his wardrobe if he wants to attract women -- and offering to help him -- shows that you're honest and positive, without being mean.

Telling siblings what they should do isn't the only way that brothers can show stellar communication skills. A good brother is an active listener, takes in what his siblings have to say and processes it before responding. Active listening involves paying attention to what the other person is saying to understand his point of view, according to the article "Families First -- Keys to Successful Family Functioning: Communication" on the Virginia Cooperative Extension website.