Developmental psychology/Chapter 8/Families During Middle Childhood

shared environment - two children (who are siblings) share in that environment, including parents and school.
nonshared environment - aspects of the siblings in which they do not share, including [usually] friend groups and clothes. Most personality traits are derived from genes and non-shared environments.

The assumption that siblings share the same environment is wrong as different aspects of life affect each child differently, according to their "age, genes, resilience, and gender". This also brings in differential susceptibility and the parents' treatment of children, which differs based on each child. We are affected by...

genes (monozygotic and dizygotic, for ex.)
shared environment (school and home)
nonshared environment (family experiences, being treated differently from each parent)

Family structure - Genetic (siblings) and legal (married) connections between family members.
Family function - How the family collectively meets the needs and functions as a group.

Children in middle childhood (6y-11y) need:

Physical necessity
Learning
Self-respect
Peers
Harmony/stability

Residential stability aka constant changes are harmful to a kid's development, as seen in the studies of homeless children's "cortisol level, blood pressure, weight, and the likelihood of hospitalization". Though, if a mother provides emotional support, kids can be resilient.
Military children may suffer psychologically when their parent is deployed. Most of these kids cope with it.

Overall, all children will need to cope with some levels of disruption - but constant changing of environments increases stress in the children.

Types of Family Structures

Single-parent family - One parent.
Extended family - Multiple generations in one household.
Nuclear family - Parents are the biological parents of the child
Polygamy family - Multiple wives of a husband, income and education is reduced and is illegal in the US
Stepparent family - Step-parent led family. The term, blended family, comes into play if there are children from the old and new relationship.
Adoptive family - Two-parent families.
Grandparents family - Otherwise known as a skipped generation family.
Same-sex family
Single mother—never married
Single mother—divorced, separated, or widowed
Single father
Sole grandparent
Extended/polygamous family - 2+ adult led family

Trend: more divorces/remarries and single-parent families, fewer children per parent than before.

Family Structure and Function: The Linkage

Usually, single-parent families are less impactful on their child as the single parent has less money, time and stability to provide. Obviously, not all types of family functions work flowlessly - there are exceptions. There is also a cultural context, with being that immigrant families may function better as an extended family vs. nuclear family. On the other hand, some families cannot function as extended families since that would be too expensive.

The two major linkage destroyers for family structure and function are low income and high conflict.

Parents shouldn't fight in front of their children, but polite disagreement is better.