Christopher Evans, 14, and Jonathan, 11, are sighted, as is their father, an engineer. Their mother, Yuen Har Tse, 46, a former business analyst now looking for work, has been blind from birth. Their parents divorced six years ago; they live with their mother in Maidenhead, Berkshire.

"I realised Mum was blind when I was three," Jonathan says. "I noticed she would bang into stuff, like the settee, and she kept walking into the things I was playing with."

Yuen Har Tse, who was born in Hong Kong and brought up in Crawley, where her parents ran a Chinese takeaway, has Leber's congenital amaurosis, a rare inherited eye disease that was detected when she was a baby. She went to specialist boarding schools from the age of seven and then studied engineering at Exeter University, where she met the man who became her husband, an electronics technician.

"When they were babies," she says, "I judged from the routine whether they were crying because they were hungry or whatever, but it got hard as they started to move about." As long as they were making a noise, her task of locating them was easier. But Jonathan was a quiet child who would get absorbed in playing with his toy figures and she was worried about tripping over him. One of his earliest memories is being taught to say, "Watch out" when his mother entered the room.

"She tried to help us build things with Lego," he says. "She'd find the right blocks by counting the little bumps on top." She could build houses because she knew how they were supposed to look, but got lost with Lego Star Wars action figures. She would also help with jigsaw puzzles. "I used to cheat," she admits. "I used to label each piece with a Braille letter, then I knew that across the top it was ABC, so I made the boys think I could see it and do it." She taught them the alphabet with magnetic letters. But supervising their reading was painfully slow. "I had to say every single letter and where the spaces were and the full stops, and then Mum would have to work it out," Christopher says. If he didn't know the letter, he would hold his mother's finger and trace its shape.

The boys' parents separated when Christopher was eight and Jonathan was five. Their father picks them up from school and they spend either two or four hours with him before going home.

"In some ways it means more freedom because Dad isn't as clingy as Mum," Christopher says. His mother admits she is overprotective. "Even when they're playing outside, for instance, I get worried because I can't just look out of the window and see that they are still there." So the deal is the boys have to report in every half an hour. "If we're playing a game like man hunt or having a race outside and we are halfway through and then I have to stop and go and check back, it can be a bit annoying," Christopher says.

As a 12-year-old, he found bringing friends home stressful. His mother likes to feel his face with her fingertips and never seemed to realise the impact of doing that in front of his friends. Worse, what if she mistook one of his friends for him and started to touch their face? "Also, she has a voice on her phone that reads texts and gives her the time, and that can sound a bit like a Dalek," he says, "so I would have to explain or pretend it didn't happen. It's not such a big deal now as my friends are older and are more mature about it. Actually, I don't think they realised she couldn't see because once one of them said, 'If your mum and dad have split up, why are they holding hands?' I was like, 'It's because she can't see and needs guiding.' "

The question their mother most frequently asks of them is to read the use-by dates on food. She relies on ready meals; she has a Braille dial on the oven and cooks vegetables on the hob as she has stickers showing various settings (she has serious qualms about frying as she can't tell when food is done). "It does get frustrating if I have to read about 10 use-by dates," Jonathan says.

There are benefits: the need to orient their mother means they are excellent at giving directions and have advanced descriptive powers. Sometimes it is also useful to be under the radar. "If I've been talking in class and there's a note from the teacher in my planner, I didn't kill anyone, so I just don't bother mentioning it," Christopher says.

Daniel and Joseph Walker are non-autistic, as is their father, Seth. Their mother, Jo, is autistic. Photograph: David Yeo for the Guardian

Daniel Walker, five, and Joseph, three, are non-autistic, as is their father, Seth, 40, a software architect. Their mother, Jo, 30, was diagnosed with autism in February. They live in Manchester.

"Mummy likes playing with me! And loving me!" says Daniel, who has just spent a typical morning with his mother. Up at six, they play with toys while their mother gets dressed. She will wear purple because she says it makes her feel safe. Half the clothes in her wardrobe are purple. "I don't wear the other half," she says. Daniel and Joseph are allowed to wear whatever they like as long as it's not made from velour because their mother hates the feel of that. She will make porridge and stop the microwave before it finishes as she dislikes the sound of its beeping. All the china and plates are arranged in size order in the cupboard, as are the boys' picture books on the shelves in the sitting room. (Each shelf has a subject category. Their bedtime story is a reference book on coral reefs because their mother prefers fact to fiction – although she also reads fiction to her children.) DVDs are arranged alphabetically. "If something is an awkward shape, it really annoys me," Jo says.

After breakfast they will play a game. She knows imaginative play is important for her boys but struggles to join in. "I don't know what to do," she explains. "I can roar and I can pretend to breathe fire, perhaps, but that's as far as it goes and then I'm stuck. Also, it bores me. Whereas if you were to say, let's play Angry Birds Space ludo, love it, it's a physical game."

Jo grew up in Luton, where her father was a lorry driver and her mother worked in a supermarket. She had symptoms of autism as a child: she made minimal eye contact and had little interest in friendships, thought in concrete terms and was hypersensitive to crowded spaces, human touch, fluorescent lights and noise. Yet she was diagnosed with autism only in February.

"Girls are much better at fitting in than boys and their obsessions are very similar to non-autistic girls'. For example, when I was a girl I was obsessed with soaps, like Neighbours and EastEnders. I knew all the characters, who played who, but apparently that is a normal thing to like."

After leaving school she trained at college to be a nursery nurse, then worked in a nursery for two years but found social niceties difficult. "I try to be polite if I can but I don't always know what is polite and what is not."

She met Seth seven years ago at a get-together for fans of the online game Bushtarion. Seth is from Manchester and liked Morrissey. "I am fixated on Morrissey," Jo explains.

A friend who has an autistic son suggested she get tested for autism. "It's a relief," she says of her diagnosis. "I am more accepting of myself."

The cliche of autism is that it impedes the ability to love. How do children engage and get comfort from an autistic mother? "I have no problem doing anything with my boys," she says. "I can hold them, have them right in my face. I am so attached to these boys." Looking anyone else in the eye, however, is "the most uncomfortable thing in the world". The other surprise is physical affection. "I am a little bit uncomfortable even with Seth on occasions. He's got a big red coat and it's made of very heavy material, and I just can't bring myself to hug him when he's wearing that. But with the boys there is nothing that would stop me hugging them, even if they were caked in mud, and to me that is disgusting."

"I really struggle reading people but with Daniel, for example, I can just look at his face and say, 'You're about to burst into tears. Why? What's the matter?'"

But there are difficulties. She becomes depressed and overwhelmed when the boys are ill. "I know what to do – have a bowl if they're going to be sick or take their clothes off if they have a temperature – but it's the fear of not being in control."

She also gets agitated when she takes them out. "There are so many noises, so many colours, shapes, moving objects, people. I am not very good at crossing the road. I sometimes stand at the side of the road for quite a long time with the boys to make sure that it is definitely safe." Seth, who works from home four days a week, helps her with the school and nursery run.

For someone with an extreme attachment to systems and order, she is teaching herself, when faced with chaos, to act "normal". Joseph broke the legs off a HexBug, a small electronic toy, during my visit. "I feel like crying because that toy is incomplete," she says. "I'm going to throw it away now and I'm going to try not to think about it. But that is going to bother me. It's going to be in my head for the rest of the day."

Ryan Pilkington and Eire McGlip-Quinlan are hearing. Their mother Lesley and father Michael are both deaf. Photograph: David Yeo for the Guardian

Ryan Pilkington, 28, and Eire McGlip-Quinlan, 17, are hearing. Their mother Lesley, 47, general manager of a translation service, is third-generation deaf; Eire's father Michael, 50, head of local engagement for Action on Hearing Loss in the east of England, was born deaf after his mother contracted congenital rubella in pregnancy (Ryan is Lesley's son from a previous relationship). They live in Amersham, Buckinghamshire.

Eire first realised her parents were different when she was at primary school. "I went to a childminder after school and in their house the parents were shouting, everyone was screaming, whereas my house was quiet-quiet." In fact her parents were communicating in a language that was vibrant, lively and nuanced. It just had no sound.

Lesley met Michael in 1989 at a European deaf youth exchange event in Amersham. Michael was the representative from Northern Ireland; Lesley, the representative from England.

Lesley grew up with deaf parents and deaf grandparents, and is one of five deaf sisters. British sign language (there is no universal one) is her native language. Michael's deafness wasn't spotted until he was two; he learned to communicate with his hearing family by gesture and lip-reading. Aged five, he was sent to a specialist boarding school in Dublin where he learned to sign.

As soon as Ryan was born, Lesley knew he was hearing. "His eyes were different," she says through an interpreter. Children who are deaf tend to orient themselves by looking all around a room; the eyes of hearing children, who can locate themselves with both sound and sight, tend to be more directed. "My mother said, 'He's got hearing eyes!'"

Neither parent could help their children acquire language. "Children learn speech by listening to nursery rhymes," Lesley says. "Obviously we had problems." Both Ryan and Eire went to a private nursery from three months: "Slightly earlier to give them the best chance to get a hearing environment." At home they listened to stories on tapes, and television assumed a central role.

Ryan and Eire communicate with their parents through gesture, facial expressions, speaking (Lesley and Michael are good at lip-reading) and sign language. The parent/child relationship is one of intense visual focus. But English and BSL are different in structure. Signing does not involve going word by word through a sentence as if it were being spoken. The focus is nouns and verbs.

Eire, who is lively and bright, is quick to learn, but by six, this was causing problems: "There was a difference in my speech compared with other children's. My childminder picked up that I wasn't saying the end of my sentences because when I'm signing I don't need to." She had extra lessons at school and plans to read English at university. But occasionally she still has problems. "Sometimes I stutter and I don't know if it's because my speaking hasn't caught up with my brain."

Michael and Lesley are eloquent, independent and confident, and Ryan and Eire are mostly only called on to answer the phone or the front door, order takeaways, buy tickets or oversee routine transactions at the bank ("Situations where there are barriers in front of the person you are trying to deal with," Ryan says). "Long ago it was normal for deaf parents to use their children to communicate with their doctor, and that can be emotionally damaging for the child," says Michael, who has been careful to maintain the child/adult divide.

Nonetheless when Eire was nine, she used to worry about her parents. "My room is on the top floor and my mum and dad are on the middle floor, and say someone broke into the house, their room is the first room they would go to, and I'd be like, 'Oh my God, how can I protect them? How can I call the police before they get hurt?'"

These days the role reversal manifests itself differently. "My dad is a noisy eater and it really annoys me, particularly in restaurants. They scrape their knives and forks, and I'm like, please! Stop it! And they don't realise they're doing it. Or my dad will burp really loudly. Oh my God!"

One of the most challenging times for Eire is when her father wakes her up. "I'm not good in the morning and he'll try to talk to me and I'll get agitated signing, and shout, then he won't know what I'm saying and I'll have to try to explain." When angry, Eire signs curt one-word answers.

The advantage is being able to play loud music – although their parents still complain. "Ryan gets in the car and turns the volume up," Lesley says. "I might not be able to distinguish between 20 and 30 on a dial but obviously he can damage his hearing. Also when Ryan gets out of the car he doesn't turn it down and everyone is going, 'Wow, look at that woman, she is digging it!'"

Rachel D'Ambrosio, is non-religious. Her parents are Jehovah's Witnesses. Photograph: David Yeo for the Guardian

Rachel D'Ambrosio, 39, a florist, is non-religious. Her parents are Jehovah's Witnesses. She lives in Peacehaven, East Sussex, with her second husband Gary, a company director, and twin daughters from her first marriage.

As a Jehovah's Witness, Rachel D'Ambrosio had a duty to spread the word: Judgment Day was imminent. "Even when I was at school, I remember my parents saying to me, 'Try to have a "little witness" with your friend Sarah or Susan.' And I'd say about all the horrible people in the world and how Jehovah would sort it all out and we'd all go and live in paradise. I remember saying, 'Don't you want to live in paradise where you are never going to be ill or get a cold again?' And they were like, 'I think it's a bit weird' and they'd draw away from me and start talking to their other friends."

Rachel's parents became Jehovah's Witnesses after a knock on their door in 1974. Her father, a builder, had grown up with the Salvation Army and Baptists; her mother was a Roman Catholic. "My mother's mother died when she was eight and Jehovah's Witnesses believe all who have died will be resurrected, and this guy who knocked on my parents' door gave my mother the hope of seeing her mother again."

Rachel's worry was that Armageddon would come when she was at school. "I'd grown up reading Bible stories with pictures of buildings destroyed and fires everywhere, and everybody crying and people dead on the street, and I used to walk to school thinking, how are my parents going to get me if everything is destroyed?"

Jehovah's Witnesses don't observe Christmas, Easter or birthdays. At school, when her friends were making Christmas cards and putting on Nativity plays, Rachel read Bible stories. "What is very sad about the religion is they take so much away from you – Mothers' Day, Valentine's Day – but they don't give you anything in return."

When Rachel was eight, she took her first defiant decision. "My friend Susan's mum called her daughter's birthday party a summer party, so I could go. My parents never knew. When it came to cutting the cake and blowing out the candles and singing happy birthday, she kept me at the back and hugged me, so I didn't feel I was doing something my parents didn't want me to do."

Rachel's life continued with this mix of acquiescence – of wanting to please her parents – and defiance. She went to the assemblies, large conventions of the movement, held three times a year in such places as Twickenham stadium and Crystal Palace. "That is when I had new clothes, like white sandals and frilly little socks, so it was a big thing." She still misses the friends she made there. She pushed herself to the fore of door-to-door preaching. "When you opened the door, I'd be the person who'd start chatting about religion. And when the door was slammed, I'd get really upset because I'd been brought up to tell you about my religion and conditioned to give out so many magazines a month."

She customised her Laura Ashley dress to please her parents. "It was beautiful, very floral, very big puff sleeves, and I loved it. It cost £60 and I had saved up for ages from my babysitting money, but it had an open-back design and my parents went mad. You had to be very modest, you had to cover up and always wear a skirt." Rachel stitched in a modesty panel.

When she was 13, her rebellious 16-year-old sister got pregnant, and the community judged her unkindly. "She was treated appallingly and I was devastated. The one time in her life she needed support, and they all turned their backs on her." Rachel felt profoundly let down by the religion. "From 13 to 17, I effectively led a double life. I had two boyfriends my parents didn't know about and I used to go clubbing."

At 19, she got baptised, and in 1995 she married David, also a Jehovah's Witness, whom she'd known for only three months before they got engaged. They had twin girls in 1999, but four years later, aged 28, Rachel chose a new life. "I thought, that's it. I'm getting me and my children out of this religion and out of my marriage." She wanted a more normal relationship with her parents, freedom instead of ritual and constraints. They have not spoken to her since 2006. And eight years on, she still feels sad. "A parent's love for their child is unconditional. You should love them regardless. But my parents' love for me is conditional, on the basis that I hop straight back into the religion."

Academically bright Alex Huntesmith with his mother, Jill, who has learning difficulties. Photograph: David Yeo for the Guardian

Alex Huntesmith, 18, is academically bright. His parents Jill, 52, and Alexander, 49, have learning difficulties. They live in north London.

Alex Huntesmith showed a precocious interest in reading magazines in the doctor's surgery at the age of two. He is now studying A-levels in law, politics, history and English literature. His real name is Quinton. His brothers are Quilliass, 16, and Qumarii, 12; his sister is Quilenn, 15. The Q is a solution to his parents' poor spelling. Ordinary names, such as John or Stephen, Jill says, are too difficult, "but because the Q is there and you've got the U, it's easy to remember. It rhymes."

Jill grew up in Stoke Newington, north London, and was diagnosed as dyslexic at seven. After leaving school unable to read, with one O-level, in art, she worked in a handbag factory, then as a volunteer canoeing instructor. She met her husband at a college for adults with learning difficulties, and they got married in 1995. He has worked as a painter, road sweeper, in a furniture store warehouse, and is now an outreach worker for Our Group Your Group, a support group Jill founded for parents with learning difficulties.

"Dad has trouble with everyday things and he finds it difficult to speak to people. Mum will eventually find her way around using signs, but Dad can't," Alex says.

The pair underwent an intelligence test when they were young adults. "My husband had a learning age of five and I was seven," Jill says. But the categories are blunt and don't convey their abilities. "Exams or qualifications don't measure intelligence, they measure your ability to remember things," Alex says. "Dad has some architectural drawings I can't imagine ever doing and mum is an accomplished artist." Jill, for her part, dislikes the word "normal". It implies "we are lacking in something. Everyone is the same really. The problems we have are slightly different."

When Alex was six, he remembers his mother asking him to read a letter from British Gas – Jill's mother would normally help with such jobs, but she was away. At bedtime, Jill would "read from her head" stories she made up. "They were great stories," Alex says. Simple things like going to the supermarket would take five hours. "They would move stuff, so you had to hunt for it," says Jill, who identifies items by design, rather than name.

"We did rely on him a lot," she says, "but when he was seven we took the responsibility away, because he was getting to be a big adult when he was young, so we'd try to do things ourselves. Then Mum died and we didn't have anyone to help." Alex now handles such things as Ocado orders, supermarket shopping, fixing the Virgin media box. "Banking is a new one." His parents, he says, are naive about money and got into debt. "It was paid off after a few years but it showed me that you just can't spend everything." For example, "the other evening we really wanted pizza. Mum was willing to pay full price which came to about £50. But I thought that was ridiculous. So I spent half an hour hunting down a voucher that got us £25 off. I was quite proud of that." He pays bills on time – phone, credit card, Netflix and LoveFilm. His mother pays 40% of his phone bill and he gets an allowance from his parents.

Jill and Alexander tried to take the family on a caravan holiday when Alex was small but had to wait for someone to show them how to work the propane gas bottle before they could cook. They arrived at midday and finally had lunch at 6pm.

"We've gone on day trips but haven't been anywhere as a family for more than 14 years," Alex says. "It was frustrating, but when I was 16 and got my first adult passport, I realised I could travel alone." He's been to Warsaw, Berlin, France, with friends or alone, and is off to New York in August.

He is keen to challenge stereotypes. "Stories in mainstream TV never show [parents with learning difficulties] in a positive way." Which is why he agreed to play himself in the BBC Radio 4 drama The Pursuits Of Darleen Fyles, about a young couple with learning difficulties who want a baby.

But there are challenges. "On holiday, say, my friends will get calls from their parents asking, 'How are you?' I'll get a call saying, 'How are you? Could you help me with this?' When my parents call, no matter what I'm doing, I have to answer."

• The Pursuits Of Darleen Fyles will be back on Radio 4 in July.

• This article was amended on 30 May 2014 to clarify some details of the interview with Jo Walker.