Using TikZ, how can I bend the edge between two nodes in a tree?

Question

I tried setting edge from parent/.style={draw, bend left=60}, but the line remains straight. What am I doing wrong?

\documentclass{article}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}[
        every node/.style={
                draw,
                circle,
        },
        edge from parent/.style={
                draw,
                bend left=25,
        },
]
\node {}
        child {node {}}
        child {node {}};
\end{tikzpicture}
\end{document}

Answer 1

Found the solution. Instead of

    edge from parent/.style={
            draw,
            bend left=25,
    },

I put

    edge from parent path={
            (\tikzparentnode\tikzparentanchor) edge [bend left=25]  (\tikzchildnode\tikzchildanchor)
    },

and it worked!