TiKZ tree doesn't grow as intended

Question

I have this code:

\documentclass{standalone}

\usepackage{tikz}
\usetikzlibrary{mindmap}


\begin{document}


    \begin{tikzpicture}[text width=2.7cm, 
        align=flush center,
        grow cyclic,
        level 1/.style={level distance=5cm,sibling angle=180},
        level 2/.style={level distance=3cm,sibling angle=45}
    ]


        \node{28 Days Later (2003)}
            child { node {Ancestors} }
                child { node {Night of the Living Dead (1968) } }
                child { node {The Omega Man (1970) } }
                child { node {The Day of the Triffids (1959) } }
                child { node {I Am Legend (1954) } }
                child { node {The War of the Worlds (1894) } }
            child { node {Descendants} }
                child { node {The Girl With All the Gifts (2016) } }
                child { node {The Walking Dead (2012) } }
                child { node {World War Z (2013) } }
                child { node {FEMA Emergency Preparedness Guide (2019) } } 
        ;
    
    \end{tikzpicture}

\end{document}

The first-level branches fan out as intended, but the second-level branches don't:

What should I be doing differently?

Answer 1

You did the bracket nesting for the map not completely right, I did a correction, but was a bit unsure where you wanted the Ancestors/Descendants exactly...

\documentclass{standalone}

\usepackage{tikz}
\usetikzlibrary{mindmap}


\begin{document}


    \begin{tikzpicture}[
        text width=2.7cm, 
        align=flush center,
        grow cyclic,
        level 1/.style={level distance=1.5cm,sibling angle=180},
        level 2/.style={level distance=3cm,sibling angle=45}
    ]

        \node{28 Days Later (2003)}
            child { 
                child { node {The Girl With All the Gifts (2016) } }
                child { node {The Walking Dead (2012) } }
                child { node {World War Z (2013) } }
                child { node {FEMA Emergency Preparedness Guide (2019) } } 
            }
            child { 
                child { node {Night of the Living Dead (1968) } }
                child { node {The Omega Man (1970) } }
                child { node {The Day of the Triffids (1959) } }
                child { node {I Am Legend (1954) } }
                child { node {The War of the Worlds (1894) } }
            }
            ;
    
    \end{tikzpicture}

\end{document}

This produces