My cousin John just sent me this picture of my great-grandfather, Joseph Mulcahy, and his younger brother Michael.
Joseph and Michael were the 4th and 5th in a family that, at the time, included 5 children. I'm not sure where their older siblings are in this photo - in 1899, Margaret would have been about 9, James 7, and Matthew 6. The picture includes only the babies of the family.
What's most interesting to me is that Papa's face really seems never to have changed. Even at the age of 3, you can see the very strong resemblance to his pictures as an adult. (Examples here and here.)