I know quite a few cases where sons in the family still live with their parents past the age of 30. In almost every case, the son has been spoiled/smothered by the parents (moreso the mother,) and been waited on hand and foot, and mollycoddled, up to (and including) adulthood. They never went to uni, they have never left the UK, they have never held down a job for more than several months, and they have never grown up.
You rarely get girls/women behaving like this. Mainly because they are not mollycoddled like boys are, and don't have everything done for them like boys. Indeed, in some families, the girls are/have been made to do housework and cooking etc, whilst the boys do nothing, because the girls need to learn 'housekeeping skills' and 'woman's work.' 
One woman I know has a 37 y.o. son who still lives at home (she is 59,) and he hasn't worked more than 2 to 3 years (in total) since he left school over 20 years ago. Currently hasn't worked for 7 years. He gets no benefits money, as it was stopped around 5 years ago, when he couldn't be arsed to stay in any job for more than a few weeks. His mother pays for everything for him. She works in a factory doing long 12 hour shifts (at 59!) to enable the bone idle fucker to carry on his sedentary lifestyle.
He is a fat slob who stays in bed til 11am, eats pizza for ' brunch,' spends all day on netflix and on the playstation, and then pisses off out to the pub for the evening, never lifting a finger in the house - ever.
I have actually known a number of families with sons/men like this. And whilst I feel for the parents a bit, I have to say that the parents DO have to take some responsibility for how their children turn out.