The story of sibling differences is the story of parental investment and any perceived biases in it. Siblings are different because they exemplify Darwin’s principle of divergence. Diversity is a useful strategy that allows species to compete for scarce resources. Given enough time species tend to evolve multiple forms that diverge in character, a process called, Adaptive radiation. By occupying different ecological niches the members of the subfamilies coexist in far greater numbers than would otherwise be possible. As children grow up they undergo adaptive radiation in their efforts to establish their own individual niches within the family. The competition over family resources and the parental affection creates rivalries. Siblings use strategies to gain a competitive edge and to maximize parental investment. They target unoccupied niches and use physical advantages in size and strength. Over time the strategies perfected by first-born spawned counterstrategies by Last-born. The result is the evolutionary arms-race played out within the family.
Young sand-sharks devour one another inside the oviducts of the mother until one well-fed shark is left alive. Such unrestrained siblicide is rare, but unbridled altruism is equally rare. Because first-born are older than their siblings and hence more likely to survive and to reproduce, they have an edge in courting parental investment. When parents are no longer able to have additional children it’s sensible for them to concentrate investment in those children who are the most vulnerable to death and disease. The losers in this Darwinian calculus are often Middle-children. Last-born fare better, because they’re the only member of the family to receive parental investment undiluted by the needs of a younger rival. Youngest children, tend to be dependent and selfish as they’re used to others providing for them. They’re also quite often the life of the party––fun, confident, and comfortable entertaining others.
Kids are smart critters—they’re always looking to whoever is above them in the family tree. A first-born or only child gets her cues from her parents. Second-Born looks at the first-born, and the baby; he watches what the first-born and middle-born siblings do and learns how to work the system. It doesn’t take long before he is pro. Middle-born is the hardest to pin down. Middle-born will be opposite of the child above him in the family. Middle-born walks to the beat of different drummer. The oldest is special simply because he’s the oldest. Mom and dad would stand transfixed around his crib each night just watching him sleep. They could hardly believe that their union had produced this new life…and such a beautiful new life it’s. This parenthood business was all so new and exciting. As for the youngest, he’s special because he’s baby and he’ll always be the baby even if he’s 6 ½ feet and weighs 100kgs. He basks in the sentimentality of being the last child. The three-kids’-triangulated-sibling-relationships, with one child, the ‘Middle-born, at any given point feels like the odd man out from the chumminess of the other two.
Middle-children are usually hampered in their expression of aggression toward their younger sibling who is typically protected as the baby of the family. In altercations with their siblings, youngest children can better afford to hold their ground because parents and sometimes other siblings intervene on their behalf. Middle-born aren’t as connected to parents as other brothers. With a first-born, the family’s schedule revolves around the baby. With the second-born, the schedule revolves around carpools for the first. When the next baby comes along, the now-middle child’s schedule gets adapted to that one. Parents tend to be much more easy-going, less anxious, and less demanding with second and third children. The key to the psyche of middle-children is their unique family niche. Middle-born subconsciously bemoan their fate as being ignored and grow resentful of all the parental attention is given to the oldest and the baby of the family. They feel short-shrift. Used to their opinions not really being asked, Middle-children usually have to fight harder for the attention of their parents and therefore crave the family spotlight.
In a family, the birth-order largely determines who shall rebel and who identifies himself with the power and authority. Just as a second child seeks to be different from the first a third the child seeks to be different from the second. As a result, ‘jump-pairs’ tend to end up being more similar than adjacent pairs. Because of the reason that they’re not usually adjacent to first-borns in the family hierarchy, last-borns are freer to emulate first-born characters including tough-mindedness. In spite of their best efforts to the contrary, parents occasionally exhibit favouritism toward some of their children. No social injustice is felt more deeply than that suffered within one’s own family. When unassuaged such feeling undermines respect for authority laying the foundations for a revolutionary personality. Middle-children make the most ‘Romantic revolutionaries’. When they rebel, they do so largely, out of frustration or compassion for others, rather than from hatred or ideological fanaticism. Feeling the squeeze from both ends – they’ve to deal with the quirks, needs and wants of older and younger sibs–what may begin as a survival skill frequently becomes a source of satisfaction. Middle-born are often the negotiators. They try to smooth the oceans of life. They often feel lost in the shuffle.
Marrying a Middle-born means invariably thriving relationships. The first-born, who thinks, he knows all and sees all, would be smart to check with his Middle-born spouse who has a nose for people like a bird dog has a nose for a pheasant in a cornfield. The gut reaction and relational skills of Middle-born will help many a first-born out of the woods. No wonder Middle-born have the best track record for building a loving marriage. Put a Middle-born with first-born and Last-born, and the ocean is much clear for sailing. That is because Middle-born children have spent their entire lives seeing both sides of children and both sides of the issue. They’ve negotiated the waters between older and younger siblings and have often had to drift between the two as the peacemaker. Middle-born having learned to be good negotiators, masters of compromise and keeping everyone happy that is why having a Middle-born in the marriage jacks up the probability of the marriage’s success.