Season 4

To celebrate their "phone-iversary" Josh convinces Sophie and Brian to buy him a new mobile phone. Sophie also gives a mobile phone to Brian, however the phone wipes his mind of all his alien memories. Meanwhile, Josh believes his mathematics teacher has fallen for him. Josh, Lucy and Wendy all discover love through texting.

On Father's Day, Sophie gets upset that she has never received any Mother's Day gifts. Brian sets out to prove he is the World's Best Dad. Josh tries to gain the new video game "Gnomes Of Vengeance" from the new girl, Poppy Manning, but she will only give games to girls. Josh asks Lucy to get the game from Poppy for him. Lucy agrees on one condition – that Josh pays her £54.60. Mel is upset when Brian thinks she is a boy. The episode concludes with Sophie attempting to be more masculine by working out and Brian attempting to become more feminine by growing breasts.

Continued from the previous episode. Brian and Sophie's attempts to embrace the opposite gender become more and more extreme. Brian tries to be a better father by becoming more sensitive, while Sophie gets in touch with her masculine side. Josh still attempts to get the video game from Poppy.

When Lucy gets in trouble with one of her teachers for apparently copying homework, Brian and Sophie discover the power of punishment. Poppy writes an article in the school magazine criticising Josh. Mel accidentally kills the school budgie and Josh writes this in his own school magazine. To get revenge, Mel gets Brian to morph into Josh and take naked pictures of himself to give to Poppy to print in her magazine.

Today Mel is fed up with Lucy's controlling behaviour and decides to move out of their bedroom and into the attic. Sophie sees this as the perfect opportunity to step in as Lucy's new sister. Lucy is incensed, but when Sophie and Wendy abandon her too, she begins to wonder whether she might be in the wrong after all. Josh is desperate to scam Frankie's signed united football shirt from him, and Brian agrees to morph into Mel as part of a cunning plan. But Josh is about to get a taste of his own medicine for once.

Brian feels rejected when Sophie chooses to watch repeats of Geoff Jefferson, Criminal Prosecutor, on cable TV, instead of taking part in his indoor Olympic Games. Josh also has grievances with Sophie's television hogging – the wrestling team have paid him in advance for tapes of special shows. This is not true. Lucy cuts the cable on the TV to end the suffering, but it ends up with Sophie putting Brian's pet rat on trial. Brian is devastated, so tries to put the blame on himself. Lucy then admits and ends up being captured and rescued on the same night.

Brian has a new pet: Fluffy the goldfish, but when she's fed on a diet of fried egg, bacon and beans, the unfortunate Fluffy soon floats off to the big fish tank in the sky, leaving Brian devastated. He then holds a funeral for his beloved Fluffy, which goes well. Josh attempts a challenge at the diner: eating 50 courses. He asks Brian to morph into him, and eat 48 of the courses. The first course is fish fingers, devastating Brian. He quits, leaving Josh to eat all the food. Mel later takes out insurance with dozens of spare goldfish, which she stores in the bathroom, and Brian thinks that the new fish is Fluffy back from the dead.

Josh is confident that his "treat 'em mean, keep 'em keen" tactics will eventually win the heart of his school friend Tanya. Sophie decides that humans tell lies all the time, making her highly suspicious of everything her family says. Mel persuades Trent to let her stand in for him as school magazine agony aunt, but can she really summon up as much sensitivity as he does? Mel's determined to prove to him that she can. In a desperate bid to prove to Josh that he can lie convincingly, Brian tells Pete that Tanya fancies him. But when Pete and Tanya arrange a date, Brian has some quick thinking to do before Josh's heart is broken. Brian discovers that lying can cause a lot of trouble, while Mel finds out that telling the truth can, too.

When Lucy insists that there's no such thing as luck (it's all just a question of mathematical probability), Brian is determined to prove her wrong. He purchases a pair of Josh's 'lucky' underpants and is delighted to immediately win a free pen and a pound.

Josh is woken by a trumpet-playing Brian and is offered tiddlywinks for breakfast. His sisters may be technically human but they still can't behave like normal people. Why can't his family just be different in every way? A bump on the head makes Josh's wish come true, throwing him into a world of complete opposites. Lucy is stupid, Mel cares about what she looks likes and fancies Frankie, Sophie doesn't even try to be a good mum, Pete is short and fancies Mel and Frankie is tall doesn't like Mel but all of the other girls fancy him. Wendy is his girlfriend and like Lucy, is thick, but more clumsier than Lucy. And Mrs. Hardman is the art teacher and fancies Brian. This leaves a whole world of confusion and he wishes that he could have been fostered by someone else. Meanwhile, the opposite Lucy and Wendy, are trying to write a story to win a day with Chubby the Bear but don't write much. And when Sophie enters too, Josh has to stop her from entering.

Lucy and Wendy have an argument that might end their friendship for ever. Josh has laryngitis, but despite Sophie's best efforts to nurse him back to health, he quickly loses patience with her bedside manner. Sophie finds that being ignored can make you feel like you don't exist at all. Brian is jealous that Trent has given Mel a music festival ticket and morphs into 'Spam' – a hip and trendy girl that will catch Trent's eye. His plan works, but Mel is devastated that Trent has found someone else. Can Josh and Sophie persuade Brian to make amends before Mel's heart is broken and Sophie turns invisible from a lack of attention? Wendy moves to Birmingham for a few months.

With Wendy away, Lucy is lonely and Mrs Hardman invites her to audition for Oliver, the school musical. Brian studies musicals by renting them all on tape. He sees that Oliver is an orphan like Lucy he thinks that this has caused offense. He speaks to Mrs Hardman and pulls the trapdoor lever so Mrs Hardman falls and breaks her legs. Brian resurrects the musical as BRIAN: The Musical. Sophie thinks that Josh has Parental Neglect Syndrome and follows him around school. Sophie then watches the Sound Of Music and learns how to really be a good mother. Mel has a bet with Trent that she couldn't last four days without insulting anybody but in the end it is Trent that breaks first and begs Mel to be mean again because that's the way he likes her!

Brian is desperate to join Lucy at the Brownies, but she refuses for obvious reasons. Undeterred, Brian forms his own association – The Brianies – with its own code of conduct. Meanwhile, Mel has got a job at the diner with Sophie later joining her to help her out...with some disastrous results.