The more one learns about Mary Somerville's childhood and early life, the more surprising her accomplishments appear. Her father had been sent to sea at the age of ten and had little formal education. Her mother read only the Bible, the newspaper, and sermons. Her parents' educational goals for their daughter were for her “to write well and keep accounts, which was all that a woman was expected to know” (PR 25) and to learn what might be called the domestic fine arts: needlework, pastry and jam making, gardening, and piano. As a child, she had great difficulty remembering names and dates and found the catechism incomprehensible. Though she could read Pilgrim's Progress at the age of eight or nine, she did not master the basics of writing and arithmetic until she was thirteen years old. She never became adept at spelling or doing simple sums.

Her family and friends generally disapproved of her penchant for reading, and she was prevented from studying Euclid at night because she was depleting the family candle supply and her family feared she would follow in the footsteps of an acquaintance who had gone “raving mad about the longitude!” (PR 54) In girlhood, her education was inhibited by old-school prejudices, lack of money, and the demands of acquiring and practicing the domestic and artistic skills required of a woman of the middle class; in early adulthood, she was limited by isolation and an unsupportive spouse.