The second problem is that the environmental factors
examined in the studies usually cited as evidence for gene - environment interactions — for example, high family
conflict (Bergeman, Plomin, McClearn, Pedersen, & Friberg, 1988), low socioeconomic status (Cloninger, Sigvardsson, Bohman, & von Knorring, 1982), or criminal parents (Mednick, Gabrielli, & Hutchings, 1987)-- can not account for differences between
siblings reared together.
There is evidence that high levels of
sibling conflict are associated with an increased risk of later internalizing symptoms.9, 14 — 17 To our knowledge, no previous studies have
examined whether being the victim of
sibling bullying is prospectively associated with psychiatric diagnoses in young adults.