It’s obvious to many of us — whether we’re an only child or not — that siblings are often different from each other.
Judy Dunn, emeritus professor of developmental psychology at Kings College London, and Robert Plomin, professor of behavioral genetics at the same institution, were among the first scholars to start empirically questioning why this happens. Drawing from differences they noticed in Dunn’s children, over the past 30 years, they’ve tested siblings’ variations in character and personality.
Finally, it seems they — and other experts in the field — have gotten closer to the answer as to why, even identical twins who live under the same roof, can sometimes end up completely different in character.
Genetics usually predicts how siblings will be different. “Because you and your brother are 50 percent similar genetically, that means you're also 50 percent different genetically,” says Plomin.
If it were this easy, siblings ...
