This example shows a family tree where each person is a labeled circle, with parent-child connections drawn as straight black lines. The root node sits at the top, followed by a generation of blood group categories and then a deeper layer of named individuals. The circles animate their radius, growing to their final size, while the links also animate into place over a short transition. The visualization uses D3.js v6, specifically `d3.stratify()` to build the hierarchy from flat data and `d3.tree()` to compute the layout. SVG elements render the circles, paths, and text labels, with color-coded fills based on the node’s depth.