The fact that siblings are of the same sex or not can influence the time that they spend with their parents, their romantic relations and the possible insurgence of anti-social behaviours
A research by Dr. McHale, teacher of the Penn State University, focused on a relation that frequently is the longest-lasting one of our life: the relationship among siblings. The research shows that parents tend to spend relatively more time with a child that is of the same sex as the parent - but when it comes to families in which there are children of both sexes, the discrepancy is reduced. When the children are of the opposite sex, nevertheless, the contrary thing happens: the male children tend to spend more time with their mother, and the female children with their father. Like the order of birth, sometimes also being of different sexes can play are role -an actual or a perceived one- in the differential treatment of children, the biggest source of conflicts and negative feelings in the relationship between brothers and sisters. The children who perceive that their brother enjoys a privileged treatment are at risk of depression and anti-social behaviours; however, these negative consequences are mitigated when the parents give a motivation to their child for such disparity: “Your brother right now has needs that require special attention”. Growing up, the relationship between brothers and sisters influences the behaviour and the development of adolescence. When it comes to romantic relationships, the adolescents who have an other-sex sibling “grow up faster in their romantic competence” as compared to those with a same-sex sibling, according to Dr. McHale. Having an older brother seems to favour the appearance of risky behaviours during adolescence, especially for boys. “The brother-brother pair can be the at-risk dyad in the sibling literature”, said McHale. “These boy-boy pairs, especially if the brothers are close in age, can be at risk for more delinquency and substances”. In the families of Mexican origin that her team has studied, “having an older sister is protective; having an older brother is a risk factor.” The relationship between brothers and sisters is formative in many ways, and parents must take it seriously, and they must be willing to monitor it directly, concludes McHale, to concretely prevent more dangerous behaviours in the future.