It cannot be known if this engaging portrait was the work of a professional or talented amateur, if it was at home (my opinion) or if it was a studio setting (if so, it is a superior example showing what can be done by a photographer who hasn't taken the easy route to knocking out commissions).
The pose and expression are casual – and did I mention engaging. These are the keepsakes that are family treasures, more the pity that it no longer is that. Early 20th century.