Line tunneling — why crossing lines in a genogram should hop, and how we automated it

The readability problem: a crossing that lies

Genograms get crowded fast. A three-generation family with a couple of remarriages, a handful of children per union, and emotional lines threaded between distant relatives produces a diagram where lines simply must cross. There is no planar layout that keeps every union, sibship, and emotional bond from intersecting. Once a family passes a certain density, crossings are unavoidable.

And a crossing is dangerous, because of how the human eye parses line drawings. When a vertical connector passes straight through a horizontal one and the two meet as a flat plus sign, the reader sees a junction — a point where the two lines connect and current, or in our case kinship, flows between them.

In a genogram every real junction carries meaning: a child dropping from a couple line, a sibling joining a sibship bracket, a partner meeting a marriage bar. A flat crossing where no relationship exists is a false junction. It tells the reader that two people are connected when they are not.

This is exactly the failure mode that makes a hand-drawn genogram hard to trust. You trace a line from a grandchild expecting it to land on a parent, and it appears to branch at an intersection halfway up the page. Was that a real connection or just two lines passing? The notation itself — see our guide to genogram symbols and the full symbols reference — gives you no way to tell a meaningful T-junction from an accidental overlap. The drawing has to solve that, not the legend.

Where the hop comes from: circuit diagrams

Engineers solved this a century ago. On a schematic, wires cross constantly, and a draftsman needs to show which wires connect and which merely pass over one another.

The classic hand-drawn convention: where two wires connect, draw a solid dot; where one wire crosses another without connecting, draw a small semicircular hop — a “wire hop” or bridge — so the crossing wire visibly arcs over the other, like a little bridge. The hop says, in one unmistakable stroke, “these do not touch.”

We want to be honest about credit here: the hop symbol is not ours, and it is not new. It belongs to the long tradition of electrical and electronic schematic drawing, where the insulated-crossing bridge has been standard for generations. What GenogramAI did was recognize that a genogram has the identical problem — distinguishing a real connection from an accidental crossing — and borrow the solution the engineering world already proved works.

The genealogy-software gap

If the fix is this well known, why don’t genealogy and genogram tools do it? Mostly, they don’t. The most telling record lives in the GenoPro user forum, where people have asked for hopped crossings for well over a decade.

Users of older genogram tools have been asking for hopped crossings since at least 2011, and the standard advice was always the same: cover each crossing by hand, and redo it whenever anything moves. No tool automated it. (If you’re weighing tools, we compare the options on our GenogramAI vs GenoPro and GenogramAI vs Family Tree Maker pages.)

How GenogramAI’s line tunneling works

GenogramAI is the first genogram maker we know of with fully automatic line tunneling. You never place a mask, never add a bend point, never think about it. The hops appear on their own, and they stay correct as your diagram changes.

Here is what the system does, in plain language:

• It hops only unrelated crossings. When a vertical line crosses a horizontal line that belongs to a different part of the family, GenogramAI draws a small semicircular arc so the crossing line bridges over the other.
• T-junctions never hop. Where a line actually connects — a child dropping onto a sibship bracket, a partner meeting a marriage bar — that is a real junction, so it stays a clean, flat connection. Only true crossings arc; real relationships are left untouched.
• A line never hops its own family’s plumbing. The connectors within a single union — the marriage bar, the drop line, the sibship bracket, the individual child stems — are all part of one connected structure. Those are meant to meet, so GenogramAI never puts a hop between a line and its own family’s scaffolding.
• Close crossings merge into one hop. When several crossings fall within a hair of each other, a row of tiny adjacent bumps would look like noise, so the system collapses them into a single clean arc.
• It covers every structural connector. Marriage bars, sibling brackets, and the staircase connectors used for multi-marriage layouts are all handled by the same logic — wherever those lines cross something unrelated, they hop.
• It recomputes as you drag. Move a person and the whole crossing map changes — old crossings disappear, new ones appear. GenogramAI recalculates the hops live, so the diagram is always correct at the moment you let go. This is the part a manual overlay could never do: static masks break the instant anything moves.

The result is a diagram that reads the way a well-drawn schematic reads — every intersection is honestly labeled as either a connection or a crossing, with no work from you. If you’re importing an existing family file, the same logic applies to generated layouts; see converting GEDCOM to a genogram for how imported pedigrees get laid out and hopped automatically.

The design debate: hops vs. junction dots

There is a live argument in modern electronics drafting worth addressing head-on, because a careful reader will raise it. Many contemporary electronics style guides now discourage the hop. Their reasoning: on a computer-drawn schematic you can guarantee that a connection is always marked with a junction dot, so any crossing without a dot is, by definition, not connected. Under that rule the hop becomes redundant — and some guides call it old-fashioned or even ambiguous, preferring to keep every line perfectly straight and rely on the dot alone.

That logic is sound — for schematics. It does not transfer to genograms, for two reasons.

First, genograms have no dot convention. There is no established notation where “a dot means connected, absence of a dot means crossing.” In a genogram a junction is shown simply by lines meeting. So the disambiguating information the schematic world moved into the dot has nowhere to live in a genogram — which means the crossing itself has to carry it. The hop is that carrier.

Second, genogram readers are not schematic-trained. An electrical engineer has internalized the dot rule and reads a dotless crossing correctly on reflex. A genogram’s readers are clinicians, students, social workers, families, and genealogists — people who have never been taught any crossing convention at all. For them a flat plus sign reads, intuitively, as a connection.

The hop is self-explanatory to an untrained eye in a way a subtle presence-or-absence-of-dot rule never could be: a line that visibly arcs over another obviously isn’t touching it. The modern anti-hop argument optimizes for a trained audience following a strict dot rule. Genograms have neither, so the old-fashioned hop is precisely the right tool.

When hops still aren’t enough

Line tunneling is a rendering fix, not a layout strategy, and it is important to be clear about the difference. The best crossing is the one that never happens. A hop makes an unavoidable crossing honest; it does not make a cluttered diagram clean. If a genogram has so many crossings that it looks like a bowl of hopping spaghetti, the real problem is the layout, and no amount of tunneling will rescue readability.

So the priority order is: minimize crossings through layout first, then hop whatever remains. GenogramAI’s automatic layout already works to place partners, order siblings, and route generations so that crossings are as few as possible — and you can nudge people to reduce them further. Recent layout work has helped here too: we now draw separated child lines per marriage so children of different unions don’t pile onto one shared drop line, which removes a whole class of crossings before tunneling ever runs. Tunneling is the last line of defense, applied to the irreducible crossings that a good layout can’t eliminate.

Frequently asked questions

Why do lines in a genogram need to hop when they cross?

Because a flat crossing looks like a junction. In a genogram, points where lines meet carry meaning — a child joining a sibship, a partner meeting a marriage bar. When two unrelated lines cross flat, the eye reads a connection that doesn’t exist. A small semicircular hop where one line bridges over the other makes it obvious the two lines pass without connecting.

Where does the crossing-line hop convention come from?

From hand-drawn circuit diagrams. Electrical draftsmen have long used a small semicircular “wire hop” or bridge to show that one wire crosses another without an electrical connection, reserving a solid dot for real junctions. GenogramAI borrows that proven convention; the hop symbol itself belongs to the schematic tradition, not to us.

Does GenoPro have automatic line tunneling?

No — users of older tools have requested automatic hops since at least 2011, but it was never added. See our GenogramAI vs GenoPro comparison for more.

Do real connections ever get a hop by mistake?

No. T-junctions — the points where lines actually connect — never hop, and a line never hops the connectors within its own family’s structure. Only genuinely unrelated crossings arc over one another, so every real relationship stays a clean, flat connection.

What happens to the hops when I move a person?

They recompute instantly. Moving a person changes which lines cross, so GenogramAI recalculates every hop live as you drag. Unlike a manual overlay — which breaks the moment anything moves — the tunneling is always correct at the moment you release.