This interactive family tree visualization displays hierarchical relationships from a JSON dataset, with nodes representing individuals and links showing parent-child connections. Users can click any node to collapse or expand its subtree, with smooth 1100ms transitions animating nodes and links to their new positions. The code uses D3.js v3’s `d3.layout.tree` for layout and `d3.svg.diagonal` for curved link paths, rendering as SVG. Nodes are styled with green circles and bold text, while collapsed nodes appear lightsteelblue. The animation is driven by D3 transitions, updating node transforms and link path geometry dynamically.