We're both only children so there aren't any brothers or sisters.
For twenty-two years I have lived amongst these pollarded trees, these rutty roads, beside these tangled thickets and streams along whose banks only children and sheep can pass.
Those persons who possess them are also apt to make spatial arrangements of days of the week or the month, months of the year, the letters of the alphabet, &c.; and it is practically certain that only children would make such arrangements of letters of the alphabet.
Birth order research focuses on five ordinal birth positions: firstborn, secondborn, middle, last, and only children.
Firstborns, after all, are only children until the first sibling is born.