Missouri at the time was a farming state. The three brothers in figure 3 were dressed in their best clothes and photographed in a studio. Some photographs from the period were taken by itenerate photographers. Farm families were photographed on their farms with their homes as a background. Notably such photographs even taken out on the farm often show little boys dressed up in dresses, often white dresses, for formal photographs.
Some photographs show families living in very primitive sod homes.
Actually dresses for little boys had some practicality in that they were easier to make than pants. The people involved were not just the genteel weaththy families of the northeastern establishment. The custom of dressing young boys in dresses cut across social and economic class boundaries. The older boy looks to be 9 or 10 and wears quite a girlish-looking dress. Surprisingly his younger brother wears a much plainer looking smock-like garment, but with lace trim at the hem.