Formal pairs suit Writing Task 2. Neutral ones work anywhere. Informal ones belong in Speaking.
1.bring up children
neutralcare for children until they are adults
Grandparents often help to bring up children when both parents work.
Raise children is a slightly more formal alternative.
Avoid: grow up children → bring up children
2.the nuclear family
formala family of parents and their children only
The nuclear family has become the norm in most cities.
The extended family includes grandparents, aunts and cousins.
3.the extended family
neutralrelatives beyond parents and children
In my country, the extended family usually lives close together.
Contrast with the nuclear family.
4.single-parent families
neutralfamilies with one parent raising the children
Single-parent families often need help with childcare costs.
Keep the hyphen. Lone parent is a British alternative.
5.working parents
neutralparents who have paid jobs
Nurseries open early to support working parents.
Stay-at-home parent is the contrast.
6.a close-knit family
informala family whose members are very close and supportive
I come from a close-knit family, so we meet every Sunday.
Excellent in Speaking. Also used with community.
7.the generation gap
neutraldifferences in attitudes between young and old people
Technology has widened the generation gap in many families.
Bridge and widen collocate with it.
8.set a good example
neutralbehave in a way that others should copy
Parents who read at home set a good example for their children.
Set, not give.
Avoid: give a good example → set a good example
9.spend quality time
neutralspend time together giving each other full attention
Busy parents should still spend quality time with their children every day.
Quality here means good, focused time.
10.do the housework
neutraldo cleaning, washing and other jobs at home
In many couples, both partners now do the housework.
Housework is uncountable. Household chores is the countable alternative.
Avoid: do house works → do the housework
11.share household chores
neutraldivide home jobs between family members
Children who share household chores learn responsibility.
Chores is countable, unlike housework.
12.care for elderly parents
neutrallook after old parents who need help
Many adults struggle to work full-time and care for elderly parents.
Look after is more informal.
13.a strict upbringing
neutralbeing raised with firm rules and discipline
My father had a strict upbringing, but he is quite relaxed with us.
Upbringing is how you were raised; it collocates with strict, happy and religious.
14.start a family
neutralhave your first child
Many couples now start a family in their thirties.
Plan to start a family is a common extension.
15.get on well with
informalhave a friendly relationship with someone
I get on well with my younger brother, even though we argue sometimes.
British. Get along well with is also correct.