These differences must then be explained entirely
by nonshared environmental effects.
The causes of incomplete concordance between MZ twins are traditionally explained
by nonshared environmental factors.
Not exact matches
The study confirmed the finding that the environment not shared
by siblings was
by far the largest (in many cases, the sole) nongenetic contributor to the adolescents» behavior and adjustment, but it eliminated all of the following as possible sources of
nonshared environmental influence: «differential marital conflict about the adolescent versus the sib, differential parenting toward siblings, and asymmetrical relationships the sibs construct with each other» (Reiss, 2000, p. 407).
«
Nonshared selves» occurred when a spouse's reported self was different from all of the other spouses» selves (e.g., the wife's possible self to «make several quilts» was not a possible self mentioned
by her husband).
In addition, links between parenting and behavior problems were largely
nonshared — reinforcing the message from behavioral geneticists that parenting functions on a child -
by - child rather than family -
by - family basis.
The
nonshared environmental influences were best modeled
by a Cholesky decomposition for internalizing behavior, whereas a time - specific influence of the
nonshared environment was included in the final model of externalizing behavior.
These factors were moderately heritable and influenced
by significant common genetic and
nonshared environmental influences.