I feel suitably admonished.

It's been three years since MIA released her last studio album, . Its first track was , a 57-second rap suggesting that social media companies were working hand-in-hand with the world's governments to spy on us ("Connected to the Google, connected to the government," she chanted repeatedly). A lot of people accused her of being politically naive. Now, following the revelations about the spying capacity of America's NSA and Britain's GCHQ, it looks as if she was stating the obvious. Does she feel vindicated? "I do. I love it." She grins.

But after that third album, MIA decided she had had enough. She was bored with music, so made the gloriously titled mix-tape (a play on WikiLeaks) in two days, just to show she could, then quit. She moved to India with her baby son, Ikhyd, and wasn't heard of for ages. Now she's back, post-retirement, with a new album, so she can tell us about her retirement. Hard to get your head around? Welcome to Planet MIA.

At 38, she still looks like a little girl: beautiful, garish, loud, a handful. She arrives with Ikhyd, now four, a sweet boy with huge brown eyes. The fact that he is here with her is a story in itself. For the past couple of years, MIA has been fighting a custody battle. Until recently, it looked as if she would lose her son to her former fiance, Benjamin Bronfman, unless she agreed to bring up Ikhyd in the US. As she says, tranquillity in her life tends to be transient at best, "the calm before the storm".

MIA emerged on the music scene in the mid-2000s, the perfect antidote to confection pop. For a start, she wrote much of her own music, an unlikely, often inspired mash of rap, nursery rhymes, bhangra, electronic dance and punk. Music writers created a whole new lexicon to describe her sound, including the fabulous "gangsta shoegaze". But she railed against commercial success, and at the first sniff of a big hit, , which made the US and UK top 20, she recoiled.

She says she grew up being told what she could do: as a girl, as the child of a single parent, as a musician, as a commodity. "If you're making music, don't talk about politics. If you're talking about politics, don't wear lipstick. If you're dancing in a club, don't talk about Sri Lanka." Sod that, she thought. "Actually, you can put the concept of freedom of speech next to rap music, next to my untouchable dad, who people talk of as a terrorist, next to random creative s***."

She was born in Hounslow, southwest London, in 1975. When she was six months old, the family moved to Jaffna, a Tamil town in Sri Lanka. She barely remembers her father Arul, although she has read plenty about him. He left to join the struggle for Tamil independence, and she and her two siblings were brought up by her mother. They went into hiding from the Sri Lankan army, then moved to Tamil Nadu in India. Just before her 11th birthday, they came to England as refugees; her mother worked as a seamstress for the royal family.

Her music has always been about family: a search for identity that often raises more questions than it provides answers. Her second album was named after her mother, . Her third album was , the name she grew up with in England. And now , her birth name. If MIA thinks the powers that be are out to get her, it's not entirely surprising. When she criticised the Sri Lankan government in 2009 for its alleged use of chemical weapons on Tamil civilians, foreign secretary Dr Palitha Kohona said she should "stay with what she's good at, which is music, not politics".

She sounds awestruck when she talks about her father. She says he was sent from Sri Lanka to the Soviet Union to study as a teenager, and he thrived in a harsh environment. "My dad grew up in a mud hut and studied by candlelight. He was 14 when he got a scholarship to Russia. He was super clever. He … was alone at 14, studying science and engineering. He didn't have a bed and he slept on a table."

Anyway, she says, the bottom line is he did screw up the family as a consequence of his political activities. In Sri Lanka, she was told that she wouldn't make anything of herself because she was raised by a single parent. There was more of this when she arrived in Britain. "At school, teachers said you're going to be f***** up, you're going to stack shelves at Tesco because you don't have a dad."

Is she angry with her father, or proud of him? "Neither. Just curious." Where does she stand on Tamil independence? "I support Tamil people, of course. I always have. Whoever sticks up for Tamil people will have my support."

The thought of losing Ikhyd must have been terrifying. I ask about her custody battle with Bronfman, whose father ran Warner Bros. She says she can't really talk about it, but of course she does - and with some anger. "In America, it's not the mother who has the say. The legal system sides with money. It doesn't side with truth, it sides with who has the best presentation of truth."

Has her experience put her off men? "No. I'm in a relationship and have been for some time, and I'm happy." In fact, she's more than happy: "I'm in a state of nirvana." Nothing is going to spoil her mood. Not arguments with her record company, which has delayed the release of the new album to the point where she has threatened to leak it herself. Nor fallouts between Steve Loveridge, the director of a much-delayed documentary about MIA, and her management.

Is the delayed release of the new album due to conflict with her record company, Interscope, or the result of personal problems? Time for another conspiracy: "Both. I thought, it's funny the s*** in my life started only when I handed my album in." The custody battle? "Yes, my personal life, and it's really hard for me to separate them." All she wants to do is get it right, MIA says. After all, so many things have turned out fine: she's back in London with Ikhyd, she has a new love, a new record and a better understanding of her place in the music industry.

"Nirvana has nothing to do with making money, nothing to do with having a number one single on Billboard, nothing to do with me sucking anyone's d***."

Was there a time when she thought she'd have to go down that route? "As a human being, you're bombarded with that image every day." Is it hard to resist? "Yes, of course it is. The only way I could do it was because I came from a f*****-up situation, so I knew how to survive on a fiver - I tasted real struggle. But if you're a kid that's grown up in England in a semi-OK environment, it's difficult. You're going to have the fear, aren't you? The assumption of darkness is scary, and that's what it works on."

Matangi