New analysis today shows that British families are shrinking but households are expanding.
According to the Office for National Statistics (ONS), almost half of parents choose to have only one child, but the fastest growing household type was those where more than one family live under the same roof.
The number of families living this way increased by 56 per cent from 201,000 households in 2004 to 313,000 households in 2014.
The ONS said: “Families in these households may be unrelated, or may be related in some way, for example a married couple with their son and his girlfriend.”
Marriage is also falling out of favour. The number of every type of household has increased in the last decade, but the biggest increase was among cohabiting couple families – up 29.7 per cent between 2004 and 2014.
By comparison, the number of married couples rose by only two per cent, whilst the number of lone parent families increased by 11.9 per cent.
Some 38 per cent of married couples had dependent children living with them, just below 39 per cent of opposite sex cohabiting couples.
People living alone now account for 28 per cent of households, up from 17 per cent in the early 1970s.
In 2014 there were 18.6 million families in the UK, according to the ONS. Just over a third of households (35 per cent) contained two people, 16 per cent had three people and 20 per cent had four or more people.
The most common household included a married couple, accounting for 12.5 million in total.
Of the 7.6 million one person households in the UK in 2014, 54 per cent of them contained one woman and 46 per cent of them contained one man.
In 2014, 7.6 million people in UK households lived alone, of which 4.1 million were aged 16 to 64.
Of those in this age group, the majority (58 per cent) were male. For those aged 65 to 74, and 75 and over, the pattern is reversed, with women accounting for 62 per cent and 73 per cent respectively.