Mary’s father, Gerrard, worked as an income tax accountant, but had always dreamed of becoming a concert pianist. He taught his two children (Mary had an older brother named Dion) to share his love of music, particularly classical and jazz. (When Mary was small, he would "play" a piece of classical music on the back of her hand and she would have to guess what it was.) Mary especially loved Peggy Lee: "I knew that I could never sound like her but I wanted to, she swung like crazy and to this day swings naturally, and it all sounds so effortless." (Dusty Springfield) Mary and Dion learned to play instruments of all kinds, including those of their own creation, and when the family had guests, they would use their father’s H.A.M. radio to broadcast into the front parlour. When Mary was old enough, she performed at school events, and when one of her teachers asked her what she wanted to be when she grew up, she replied: "I want to be a blues singer!"

Mary’s mother Catherine Anne Ryle - Kaye - also had a strong love for music. In her younger days, she wanted to be a world-class entertainer, "but she never got further than dancing in ‘am-dram’ shows." (O’Brien, 4) Wanting to be a "good Catholic girl" she settled down and married Gerrard, though they were never happy together and fought like crazy. "Somehow I took whatever criticism there was very much to heart. I have an ambivalent relationship with my brother. Our house was full of ambivalence. Raging ambivalence! We none of us wanted to be there." (Dusty Springfield) When Kaye would get bored sitting around the house, she and Mary would take off for the movies, usually American musicals. Mary loved the glamour and excitement of the movies and dreamed of going to America. Her favourite star was Alice Faye. Later, as glamour girl Dusty Springfield, she would use these early influences to enhance her image, which she built using drag queens as models: "Basically I’m a drag queen myself." (Dusty Springfield) Though she had a lot of influences, Dusty’s look was all her own. The ‘panda eyes’ and platinum blonde beehive, and white lipstick were instantly identifiable with Dusty, and they were a far cry from plain, bespectacled Mary O’Brien. "I used so much hair spray that I feel personally responsible for global warming." (Dusty Springfield) "Basically I wanted to become someone else…So I became someone else." (Dusty Springfield)

Music was not the only thing Mary inherited from her parents. When she got angry or frustrated, she would throw things (usually food or crockery) at the walls or at other people: "The door was closed, and behind it we could hear someone yelling and breaking glass. At that point, I was starting to change my mind. As I turned around to make my exit, I saw the other acts standing in their doorways laughing at me…The room was a mess. In the centre of it I saw a cardboard box full of broken cups and saucers, a few dessert plates yet intact. She had obviously been throwing some of these upside the wall." (Martha Reeves) At O’Brien family gatherings, the brussels sprouts often became airborne: "Last Christmas I sat in my flat, Tom sat in the flat below and Vic sat in the flat below that, and we ceremoniously threw the remains of our Christmas dinner out of the windows, one on top of the other. We did it just to hear the ‘shlonk’ as it hit the ground! Vic was doubled up in hysterics as brussels sprouts came thudding past his window!" (Dusty Springfield)

Mary also had odd sleeping habits, often staying up all hours of the night, no matter when she had to be up in the morning. This was one of Kaye’s traits. "She’ll be mooching around, sitting watching telly when we’ve gone to bed at twelve. She honestly cannot sleep normal hours, regardless of what time she’s meant to get up. That’s been bred into her." (Pat Rhodes)