Two of his current films tackle big issues – racism and the theory of evolution – but it is the third, Inkheart, which sees actor Paul Bettany face his toughest critics: his children.

IN ONE of those Tommy Lee Jones-winning-an-Oscar moments, Paul Bettany is finding himself having to explain to more and more people that he's not actually bald. The 37-year-old actor may have been spotted recently sporting a hairline more reminiscent of Ron Howard (his director on A Beautiful Mind and The Da Vinci Code), but his follicle issues are all in the service of his latest role as Charles Darwin in Creation, which he's currently shooting at Pinewood Studios alongside his

Bettany reckons it's an interesting time for a film like Creation, which focuses on the 20-year period in Darwin's life during which he sat on his findings about evolution before beginning to write On the Origin of Species. "There was a poll taken recently in England and an astonishing 29 per cent of teachers thought Creationism should be taught alongside evolution, which is shocking!" exclaims Bettany, incredulous. "It puts us all in a position where one can't just point the finger at America any more. It's an extraordinary poll (result]." Still, it could be worse. Sarah Palin – also on record as a proponent of teaching both – could have been heading for the White House.

Actually, the recent US presidential elections provide an interesting context in which to view another Bettany film, The Secret Life of Bees, which is due to be released in the UK on Friday. Though at heart it's a sentimental weepy based on the best-selling novel by US author Sue Monk Kidd, its setting – America's Deep South, circa 1964 when the then-president Lyndon Johnson was signing the first Civil Rights Act – ensures the racial tension of the era is never far away from the main story, which revolves around a 14-year-old girl called Lily (Dakota Fanning) who takes refuge from her abusive father (played by Bettany) on a honey farm run by three sisters (Queen Latifah, Alicia Keys and Sophie Okonedo).

An early scene in the film that sees Lily's African-American nanny (played by Jennifer Hudson) being beaten and then jailed as she attempts to register to vote provides an especially stark reminder of how far America has come in the past 40 years. "Yes, it's a period in American history that people now think is very much over," warns Bettany, "but one only has to look at the extreme right-wing backlash against Obama to see that it's still a very prescient issue. Making the movie, it was important to try and lose your 21st-century sensibilities and place yourself in an era where you wouldn't find such abuses shocking."

That was particularly important for Bettany's character, T Ray Owens. "I don't think he's the sort of man who would think of himself as a racist, but obviously racism is ignorance and he is an ignorant human being. I'm sure he just sees himself as a businessman, which I suspect a lot of racists in that era did," says the actor.

It's a small but powerful role, and a complete contrast from the other film Bettany has coming out next month: an elaborate new children's fantasy adventure called Inkheart. Based on the first in a series of novels by German author Cornelia Funke, Bettany plays Dustfinger, a fictional character reluctantly brought to life in the real world. "He's sort of a cowardly hero," says Bettany, who had to learn to juggle fire for the role – only for it to be added in later via CGI. "I think of him as a mixture between Han Solo and Scooby-Doo: he's initially just out for himself and is a little bit selfish, which is sort of a fresher approach for a character in a children's film."

Inkheart is very much geared towards the Harry Potter market, especially with its big-name Brit cast, which in addition to Bettany includes Helen Mirren, Jim Broadbent and Andy Serkis. The end result is a little bit uneven, but Bettany is good value, which will doubtless come as a relief to at least one member of his household. "I got sent the script at the same time that my eldest son Kai was reading the book," he admits, "and in an incredibly weak-willed attempt to make him think I was cool, I did it."

Having also played Silas, the self-flagellating killer albino monk in The Da Vinci Code, does he feel additional pressure playing characters from books with such devoted fans? Not really. "I think that just gives you a freedom. You just have to realise that you can only really do it your way. I just hope people enjoy seeing what I saw when I read the books."

Though Bettany turned out to be one of the few praiseworthy elements in The Da Vinci Code, he says the surrounding hoopla didn't really affect him. "There was a lot less craziness than people were expecting." So he was never mobbed by devoted "Code-breakers" then? "No, no. Eh, people might say, 'Well done' – and if they didn't like what I did, they didn't come up and talk to me.'"

Avoiding the trappings of fame seems to be something Bettany has excelled at – no mean feat considering the rapidity of his career ascent after his amusing breakout (and buttocks-out) performance as Chaucer in A Knight's Tale in 2001. Put it down to British reserve and modesty ("It still surprises me I get employed"), but even though he's played major roles opposite the likes of Nicole Kidman (Dogville), Russell Crowe (A Beautiful Mind, Master and Commander) and Harrison Ford (Firewall) he seems far removed from the Hollywood circus. Even his marriage to Oscar-winning actress Jennifer Connelly hasn't propelled him into the realms of celebrity. Then again, they do live a quiet family life in New York rather than LA.

With two young children, they also do their best to alternate work schedules – although Creation is allowing them to work together for the first time since they met on 2001's A Beautiful Mind. "In some ways it's a lot easier. It's certainly nicer being able to wake up together rather than in some other country on your own," says Bettany. "But it also makes being with your children more difficult because you're both on set all day. Normally we do try to work one, then the other, though I would never hold Jennifer to that."

Maybe he needs to find more roles like Jasper, the voice of Robert Downey Jnr's computer in this year's astronomically successful Iron Man. "Yeah, my involvement was sort of two hours really. (Iron Man director] Jon Favreau is an old mate and we sort of made jokes over the phone, did the lines in between and somehow that was it done. It was fun," he laughs, "And very easy money."

• The Secret Life of Bees is in cinemas from Friday. Inkheart follows on 12 December.