Reflow TikZ Forest from West-East to North-South

Question

I have the following TikZ forest:

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{arrows,positioning,automata,fit}
\usepackage{forest}
\tikzset{
    >=stealth,
    auto,
    thick,
    node distance=2.5cm,
    transform shape,
}

\begin{document}
\begin{forest}
for tree={
    child anchor=west,
    parent anchor=east,
    grow=east,
    draw,
    thick,
    rounded corners=1mm,
    anchor=west,
    edge path={
    \noexpand\path[\forestoption{edge}]
        (.child anchor) -| +(-5pt,0) -- +(-5pt,0) |-
        (!u.parent anchor)\forestoption{edge label};
    },
}
[Bill
    [Bob
        [Rich
            [Sam]
            [Susan]
        ]
        [Patty]
    ]
    [Mary
        [Mike]
        [Kathy]
    ]
]
\end{forest}
\end{document}

Which generates the image:

The tree 'flows' from west to east. I've been playing with the anchor settings to see if I can get it to grow from north to south with the lowest node being the one labeled by Bill (like a standard family tree), but I can't seem to make the edges look right and not overlap.

Any suggestions?

Answer 1

Too long for a comment. The "flow" of your tree is controlled by the key grow=east, but you seem to want grow=south. Then you need to adjust the anchors of parents and children, as you anticipate. Note that your \tikzset{...} stuff has no effect, so I dropped it.

\documentclass[tikz]{standalone}
\usepackage{forest}
\begin{document}
\begin{forest}
for tree={parent anchor=south,child anchor=north,
    draw,
    thick,
    rounded corners=1mm,
    edge path={
    \noexpand\path[\forestoption{edge}]
        (!u.parent anchor) --  +(0,-5pt) -|
        (.child anchor)\forestoption{edge label};
    },
}
[Bill
    [Bob
        [Rich
            [Sam]
            [Susan]
        ]
        [Patty]
    ]
    [Mary
        [Mike]
        [Kathy]
    ]
]
\end{forest}
\end{document}

An arguably easier way to obtain (almost) the same result is to just use forked edges, which are available if you load the edges library, i.e. \usepackage[edges]{forest}.

\documentclass[tikz]{standalone}
\usepackage[edges]{forest}
\begin{document}
\begin{forest}
forked edges,
for tree={grow=south,
    draw,
    thick,
    rounded corners=1mm,
}
[Bill
    [Bob
        [Rich
            [Sam]
            [Susan]
        ]
        [Patty]
    ]
    [Mary
        [Mike]
        [Kathy]
    ]
]
\end{forest}
\end{document}