They take the moral high-ground because of their ideologies and expect everyone to appreciate their actions, however the two are just as hypocritical as much as they are pretentious (as displayed in one strip when they began a campaign against slavery but then employed unpaid interns to do the work for them).
Each story finds them forcing their children into some new ethically aware activity that ostensibly encourages a policy of togetherness but ends up with Tarquin and Guinevere often escaping to their much more realist Uncle Eddie (Cressida's brother) who supplies them with ice creams and trips to theme parks.
Lured by Cressida into a new world of progressive ideological debate (and sex), Malcolm abandoned his dreams of becoming a future Tory Prime Minister and grew a beard.
He is caught in the den playing pornographic computer games such as "Deth Fuck" and "Karate Whores Must Die" whilst leering and salivating wildly.
This character is referred to as a patronising git, as all he does is talk to people as if they are stupid, or point out to the whole street that a girl on crutches is disabled and unable to speak up for herself.
Tarquin is the elder child, aged about twelve, often the voice of common sense, a very effective foil to Malcolm & Cressida due to his desire for normality or to make money.
His diplomatic ability is a means of resistance to parental authority diametrically opposed to their schemes: he is calculating and methodical in his manipulation of Malcolm & Cressida.
As a result, he is very sceptical about ideas such as crystal healing or rebirthing, questioning their rational basis, even asking a practitioner of "Wan-Ki": "Where did you get your diploma, University of Mumbo-Jumbo?"
Wanting to avoid gender stereotyping, Malcolm and Cressida occasionally try to make one or both of their sons wear girls' clothes or take "female" roles in some psychobabble ceremony.
Malcolm and Cressida have many friends, notably Ashley and Cordelia in the Ethically Aware Parents Support Group, who, like them, are middle-class, politically correct and often into various causes.
Cressida's brother, Edward – more commonly known as simply Uncle Eddie – acts as a counter-weight to his sister and brother-in-law and treats his two nephews, Tarquin and Guinevere, like normal boys.
'Guest' characters include Dr Earnest Rabbitt (who is firmly opposed to killing animals) and Professor Ruth Lesscow (an extreme women's rights activist).