Assume the MWE listed below.
This will produce the following picture. As you can see the vertical line is not 100% vertical.
Question 1: How do I say 'from point x go vertical up and connect to node y where exact anchor point at node y is unknown.' ?
Question 2: More general question: see screenshot below. What is the easiest way to make 'advanced' connections based on only vertical or horizontal lines? See the Blue line.
\documentclass{minimal}
\usepackage{tikz}
\begin{document}
\usetikzlibrary{positioning}
\tikzstyle{st1}=[rectangle, fill=white,draw=black,text centered, anchor=north, text=black, text width=4cm]
\begin{center}
\begin{tikzpicture}[node distance=1cm]
\node (Parent) [st1] { \textbf{Parent} };
\node (hidden1) [text width=0.5cm, below=of Parent] {};
\node (Child) [st1, right=of hidden1,xshift=-2cm] {\textbf{Child}};
\draw (Child.west) -- ++(-0.2,0) -- ([ xshift=-0.8cm] Parent.south);
\end{tikzpicture}
\end{center}
\end{document}