This example shows a three-generation family tree with colored nodes representing grandparents, parents, and children, connected by curved links. The code converts flat family data into a hierarchy using `d3.stratify`, then lays it out with `d3.tree()`. Nodes are rendered as SVG circles with name and generation labels, while links use `d3.linkVertical()` to draw the connections. A `d3.scaleOrdinal()` maps generations to distinct colors.