During the nineteenth century, both boys and girls wore dresses for the first few years. Before toddler boys graduated to tunics or trousers they wore full skirted frocks over starched petticoats and drawers until they were about three years old. To differentiate a boy from a girl, often a front buttoned fastening rather than the usual back closing was designated for boys in addition to diagonal trimming and pleats. See outfits here.
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