This fork of a family tree visualizes blood group inheritance through a hierarchical tree layout. Nodes are circles representing blood types (A, B, AB, O) and their Rh factor variants, with color indicating generation depth. The visualization uses D3.v6’s `d3.stratify()` and `d3.tree()` APIs to compute the layout, while SVG paths animate edges over one second via `transition().duration(1000)` as they draw from parent to child. Each node’s label is placed directly on the circle, and the palette shifts from dark red for the root to light red for deeper levels.