But families have changed dramatically in the rich world...

...over the past 50 years

You may kiss your wonderful life partner and your wife...

He knows he has a donor

He knows that we're both his parents

He knows he doesn't have a dad and all of that...

...and it's just normal

Changes to society mean that the old model of a breadwinning husband...

...and a stay-at-home wife has all but collapsed

A single mum supporting my own children is the normal nowadays

And the different ways rich and poor families raise their children...

...are increasing social inequality

We are basically paying for pre-school what I paid for college

50 years ago, families didn't look like this

We're so gay

We work together

We live together...

...and love it

Today, gay families like Maggie and Joelle's...

...are widely accepted in the rich world

There are so many gay families in San Francisco

It's amazing

It is becoming increasingly normalised

Who is in this photo?

A generation ago, it was almost unthinkable...

...that same-sex couples would get married

Look at this one

This one's really pretty...

...I like this one

You're pretty

But now most people in rich countries think gay marriage is fine

I really, really wanted our families to accept our marriage as a marriage...

...and not just like a girlfriend and I think until that time...

...I swear, I think my family just thought I was in a phase for 15 years

You were right, the wedding definitely had that effect on our families

They're in it with us now

Fears that gay marriages would undermine heterosexual ones...

...have proven unfounded

And this is one reason why marriage equality has spread...

...so extraordinarily fast

Before 2001 gay marriage was not legal anywhere in the world

Since then, it's been legalised in nearly all rich countries...

...and developing nations are starting to follow suit

In California the right to get married was on and off...

...but I think two months before our wedding was...

...when it became permitted

So that was the big part of our ceremony

It's a far cry from the 1960s, when families typically consisted...

...of a dad who went to work...

...a stay-at-home mum and three or more kids

Better access for women to contraception...

...education and jobs has changed this traditional family portrait

Across the globe, families are shrinking

Nowhere more so than in South Korea

Here a growing number of women...

...are rejecting marriage and having children altogether...

...like Go Lee, who is 26

It's Thursday night and I'm with my friends

Like many South Korean women, Go and her friends are well educated

We're going to have Mexican food which is my favourite...

...and maybe go to karaoke after this

She says traditional employers make it hard to combine a career...

...with marriage and motherhood

I decided not to get married because...

...first, career-wise when I had my first job...

...there was a senior colleague whom I respected a lot

She was devoted to work initially

Suddenly she switched focus to her family...

...and I saw her having a career break and her career stalled

Go works in IT, but is also a vlogger on YouTube, where she urges...

...South Korean women to be more assertive

The problem is that the way you hold yourself is gender specific

Women tend to be more passive and confined in the way they stand

She believes South Korean men are part of the problem

Many expect their wives to do all the housework...

...and childcare, even if they have a job

The old patriarchal society in South Korea is the fundamental reason...

...why many South Korean women in their 20s and 30s...

...like me, are choosing not to get married

Men view women as an “assistant”

At home, women need to be the homemaker and feed the family

There is a huge mismatch of expectations around marriage in South Korea

Most men want a 1950s-style relationship...

...whereas women want something more modern and equal

The result is they often end up not marrying or having kids at all...

...and that's left South Korea with a problem

Its population is in free fall

In 1960 the average South Korean woman had six children

In 2018 that figure shrank to less than one

A fertility rate of one means each generation...

...is half as big as the previous one...

...and in South Korea this means there are fewer workers...

...to support the country's ageing population

In rural areas, men are viewed as poor prospects by South Korean women

So the government is helping these men...

...to find brides from poorer countries

State-funded assimilation centres like this, teach immigrant...

...brides how to cook Korean food...

...how to speak Korean...

...and even how to deal with Korean mothers-in-law

Say it with me

Like most of her classmates studying here today...

...19-year-old Nguyen Thi Cam Thuy is from Vietnam

She recently married a South Korean man...

...40-year-old Kim Dae Hyun...

...who found her through a matchmaking website

I saw my wife's picture around September...

...and knew that she was the one

I contacted the agency and went to Vietnam

Over a fifth of married South Korean farmers and fishermen...

...have tied the knot with a foreigner

We got married last October on the 30th...

...and we are enjoying married life in South Korea

We don't have any children yet

But cross-cultural unions can be difficult...

...and around a fifth of marriages between South Korean men…

...and foreign women end in divorce within four years

This video of a man beating his foreign wife caused widespread outrage

50 years ago in most rich countries...

...domestic violence was considered normal

Now, it is universally condemned and rates have fallen sharply...

...by three-quarters in America alone, since the mid-1990s

Today, other factors are more likely to affect the stability of families...

...and these are contributing to a growing gulf between...

...middle-class and working-class families

In most rich countries, if you don't go to university...

...you are more likely to have kids outside of marriage

And women who don't finish high school are more likely to end up...

...as single mothers than women who have a degree

I'm a single mum because at 20-weeks pregnant...

...Dad decided that he didn't want to be around no more

So, I let him walk

It was easier to let him walk then than it was for him...

...to actually build an attachment with the kids and then walk

In Jamie's hometown of Hartlepool...

...in north-east England, 70% of babies are born outside marriage...

...like her twins, Sean and Liam

I am the sole earner of the household—without my income...

...and my kids interrupting me

Oh get him, fetching me cucumbers because they're awesome

It can be a financial struggle

In Hartlepool in the 1960s...

...men did heavy work in shipyards and factories...

...which was much better paid than any job their wives could find

So the women stayed at home with the kids

But as technology advances...

...manual work has dried up and uneducated men...

...have struggled to find good jobs

Everything industrial here in Hartlepool is gone

There's nothing left

What comes with industrial decline?

Poverty, depression, anxiety

Family break-ups, marriages separating, suicide

There's all sorts that come...

...because people feel they can't provide for their family

If the only men available lack steady jobs...

...and don't help around the home...

...some women feel they are better off alone

It can be hard to be a man

I presume it would be hard you know having to step back a little bit...

...and realise that you might not be the breadwinner and that you are...

...actually having to rely on a woman...

...to feed the family and keep the roof over their head

So yeah, it can be hard for a man

Middle-class families have remained solid in rich countries

...over the past 50 years...

...while working-class families have grown much less stable

Women with a university degree...

...are more likely than women who do not finish high school...

...to be married and raise children with their husband as a team

And this is contributing to a growing social divide...

...a divide that's increasingly apparent in the very different ways...

...middle- and working-class families are raising their children

Although American fathers from all backgrounds...

...do much more child care than the previous generation...

...today wealthier fathers spend much more time...

...with their kids than their poorer counterparts do

Most of the weekdays, for example, my wife takes care of them...

...taking them to school, picking them up and then when I come from work...

...I feed them, I play with them a little bit and give them a bath...

...and put them to sleep...

...and during the weekends we switch a little bit

My husband always comes back home and takes care of dinner...

...sometimes or breakfast during the weekend

So, it's very like 50/50 I would say

Harvard-educated Gerardo shares the child-care duties...

...with his wife Perla, who also studied there

The couple are investing time and money...

...in stimulating their children intellectually

We do take her to, for example, like abacus classes after school...

...where she's like starting to learn how to do additions and subtractions...

...and sometimes we come home and do a little bit of extra work

By the age of three, the children of professional families...

...have heard 30m more words...

...than children from poorer backgrounds

From zero to five, it's very important that you spend time with your kids

From there, it's like you feel they already have the values ingrained

A child's early years are the most important for cognitive development...

...so children of professionals have a head start long before they start school

The pushy middle-class style of raising kids...

...is sometimes called intensive parenting

So intensive parenting is the idea that parents are investing...

...an enormous amount of time and energy in their...

...children's development early on

Sean Reardon is a professor of poverty and equality in education...

...at Stanford University...

...and has studied the influence of class on parenting...

...and how well kids do in school

It's as if you thought of your child as an orchid...

...a delicate flower that needs daily attention...

...as opposed to thinking of your child in the way that parents used to...

...think of their children as a tree or a bush

We don't water the trees or the bushes...

...it's in their nature to grow...

...and barring any sort of catastrophe, they'll do just fine

Middle-class parents not only talk more to their children...

...and take them to ballet, chess and extra maths classes...

...they also compete to get them into the best schools

Actually her school is less than a mile from here

It's a bilingual school

They have teachers full-time Mandarin and full-time English

All of them have master's degrees and very high level education

Gerardo and Perla's daughter, Elizabeth, is learning five languages...

...including Mandarin

I think going to the school she's gonna be more open to...

...learning and talking with people like turning around...

...and speaking Mandarin and turning around and speaking Spanish

Elizabeth, how do you sing happy birthday in Chinese?

But all this education doesn't come cheap

Elizabeth's pre-school costs $31,000 a year

Definitely costs of day care and pre-school...

...have been way more than we expected originally

We are basically paying for pre-school what I paid for college

So, in the richest communities in the United States the average...