Charlize Theron and Sean Penn can't hide their affection as they cuddle and dote on her two-year-old during beach stroll

They're both very serious actors and activists, and understandably keen for their relationship not to overtake their work in either field.
So Sean Penn and Charlize Theron have been careful not to showcase their deepening romance, until now that is.
It seems that the loved up couple couldn't keep their hands off one another as they enjoyed a windy beach stroll with the South African's son, Jackson, two.

So in love: Charlize Theron can't contain her affection for boyfriend Sean Penn as they enjoy a beach stroll with son Jackson in Malibu on Sunday

He's technically 38-year-old Theron's son, of course, but 53-year-old Penn looked for all the world like little Jackson's father as the pair doted on the adopted cutie pie.

The couple - who had been grocery shopping on Saturday - were also joined by Theron's two rescue dogs, Berkley and Blue... who also looked close to Penn.

The 38-year-old actress' son Jackson was the focus of the day, however, and it was adorable to see how hard man Sean doted on the toddler.

Besotted: Charlize couldn't have looked happier as she gazed at Penn

'It's in his kiss': The two moved in for a smooch on the windswept and rainy beach

Father figure: Sean tenderly placed a kiss on Jackson's head

Charlize obviously thought so too, as she kissed her man square on the lips at one point.
The couple were wearing similarly low-key outfits to those selected for the shopping trip, though Jackson was in a bright red - and very visible - jumper.
Both were in boots suitable for the rocky terrain.

Just the four of us: Charlize hugs Sean as her dogs Berkley and Blue trot ahead with Jackson

Mama bear: Charlize scooped a giddy Jackson up in her arms

One big happy family: Sean, Charlize, their two dogs and Jackson check out the marine life

The couple have gone public about their romance within the last couple of months, with Sean far from shy about expressing his adoration for his new girlfriend.

Charlize stayed close to her man as Sean hosted his Help Haiti Home gala at The Montage Hotel in Beverly Hills on January 11.

It was there that the actor confirmed his romance with Charlize to Piers Morgan by telling the CNN host: 'She's a keeper, that's for sure... well, I'll do my best to keep her anyway.'

Adorable: Yes, that's tough guy Sean Penn looking at a rock pool with a two-year-old

Protective: Sean held onto the little man's hand as they scrambled over the rocks

Time to home: The gorgeous new family pack on the beach to head home

Sean also paid tribute to the South African beauty in a speech he made before auctioning off a Jeff Koons sculpture crafted from the 67 guns he previously owned.

'I'm a self-proclaimed Alpha male who owns 67 firearms,' Penn told the star-studded audience. 'But I've had my mind changed about guns by a strong woman, a beautiful South African woman.

'I don't need these cowardly instruments of violence and destruction, none of us do.'

Happy shoppers: The couple stocked up at Pavillions in Malibu together