I first encountered geckos with the Marbling phenotype around 2024.

Like many of you, what drew my attention at first was their unusual yet strikingly beautiful appearance—something that felt distinctly “different.” Out of curiosity, I began asking around, searching for information, examining examples, and before long, I found myself wanting to reproduce this phenotype as well. I gathered babies that looked similar, kept entire lines that produced Marbling-like offspring, and raised them myself. I carefully studied Lil Monster’s published material and listened to the opinions of various breeders in Korea. Eventually, I decided to go straight to the source—to hear directly from Yoonju of WithGecko, who first discovered and developed Marbling. Before diving into the main discussion, I want to express my sincere gratitude to Yoonju for openly sharing such a wealth of information without reservation.

1. Where Marbling Began — “Sorang”

Marbling began in 2022, from a single individual named Sorang. It displayed a pattern that looked as if it were “splitting apart,” combined with a translucent body—something intriguing and unfamiliar. At first, it was even mistaken for a low-quality Lilly.

But as Sorang grew, it revealed a completely different and unique phenotype, which led to the thought:“Could this be the beginning of a new morph?”

2. The Visual Characteristics of Marbling

The key characteristics of the Marbling phenotype include:

• Complex, fractured lateral patterns(These can occasionally appear as simple variation in other animals; my own collection has many showing similar traits.)

• A translucent, almost see-through quality

• A wine-colored underside with red tones blended with soft lavender

• A head pattern that appears split or scattered like a galaxy

  
  

To understand how these features inherit, WithGecko began experimental pairings.Considering that Sorang was a female, I imagine the process was even more challenging.

As seen in the photos, Sorang’s appearance is far from that of a typical Lilly, and this led to many possible hypotheses being tested across various Lilly combinations.The results were as follows:

3. WithGecko’s Marbling Breeding Outcomes

Marbling × Lilly→ Marbling, Marble Lilly, Lilly, Normal, Leucistic (the lethal form from Lilly × Lilly)

Marbling × Normal→ Marbling, Normal, Marble Lilly

Marbling × Marble Lilly→ Marbling, Marble Lilly, Lilly, Normal, Leucistic

Marble Lilly × Normal→ Marbling, Marble Lilly, Lilly, Normal

※ From the above lines: Lilly × Normal → Lilly, Normal

4. A Key Point — The Emergence of the Leucistic Form

What especially caught my attention was this:A leucistic (Lilly superform) appeared from Marbling × Lilly.

This leucistic is not the Genetic Super Hypo leucistic, but the lethal Lilly × Lilly form.

Naturally, this led me to think:

“The gene that produces the Marbling phenotype must be interacting with the Lilly gene.”

But something even more fascinating exists: the Marble Lilly phenotype. A Lilly-form gecko that still expresses clear Marbling traits.

Why, then, does the leucistic “superform” appear?

5. My Hypothesis — “A Gene That Is Closely Related, but Not Identical”

What follows is purely my hypothesis, not a definitive truth.

Superforms typically appear in dominant morph structures. Some well-known examples include:

• Lilly → Lethal Leucistic

• Genetic Hypo → Leucistic

• Cappuccino → Super Cappuccino

• Sable → Super Sable

• Cappuccino × Sable → Luwak

  
  

What interests me most here is Luwak—a superform that appears not from one morph but from the interaction between two separate morphs (Cappuccino and Sable).

This implies the two morphs are genetically close but not identical, interacting in a meaningful way.

I suspect Marbling × Lilly producing a leucistic form may follow a similar structure:

“Genes that are similar but not exactly the same interacting to create a super-expression.”

Otherwise, the Marble Lilly phenotype would be difficult to explain.

6. The Relationship Between Marbling and Pied

Another important point is the similarity between Marbling and the recently discussed Pied phenotype.

Although the Pied described by Oint Reptile differs slightly in form, Marbling also contains pied-like characteristics, such as:

• Transparent “broken” areas around the feet or belly

  
  

Comparing the two:

The structural similarity is clear.

The difference lies mainly in degree:

Oint’s Pied displays much larger transparent regions, whereas Marbling generally shows smaller ones.

This led me to wonder:

“Could Phantom-related genetics be involved?”

This is speculative, but patterns in Pixel suggest something similar: Pixel appears recessive only because Phantom, which is recessive, is required for its expression. It is an independent incomplete-dominant gene, and the phenotype that includes Phantom is what people typically refer to as “Pixel.” The gene itself presents differently in non-Phantom animals. This aligns with GeckoLogical Tom’s hypothesis, which proposes that Pixel is not just a pattern variation but the expression of a separate inc-dom gene whose visual outcome changes depending on whether Phantom is present.

If we hypothetically assume:

• Marbling-type Pied → Phantom present

• Oint-type Pied → Phantom absent

then the following makes sense:

• Why Marbling may have a “superform-like” expression

• Why the extremes seen in Pied Superforms rarely appear in Marbling

  
  

I personally think the Pied Superform may resemble a “full Coverage Lilly”—an extremely amplified expression.

For these reasons, I believe Marbling and Pied share a closely related genetic structure, and Marbling may well be another expression within what people now call the Pied complex. To add one more personal thought, if Pied from Oint Reptile were paired with Phantom to produce het Phantom offspring, and those het animals were later bred together, I believe there is a reasonable possibility that geckos showing a phenotype very similar—or nearly identical—to marbling could emerge from that pairing.

7. Polygenic Inheritance and Marbling

The recent discussions on polygenic inheritance also align well with the Marbling–Pied structure.

Polygenic traits:

• Are influenced by multiple genes

• Produce a wide spectrum of outcomes

  - This phenomenon is observed consistently in both Pied and Marbling.

• Typically show intermediate expressions more frequently than extremes

  - From what I’ve heard, strongly expressed ‘extreme Marbling’ is not commonly produced.

• Are best described by tendencies rather than fixed Mendelian ratios

  
  

This matches Marbling perfectly. Extreme Marbling expressions are indeed uncommon, and the phenotype varies widely.

To me, this strongly suggests Marbling is not a single-gene trait but the result of multiple interacting genetic factors.

Conclusion

In unraveling the mystery of the Marbling phenotype, I was deeply moved by the extensive experimentation, open conversations, and persistent efforts that WithGecko has invested over the years.Exploring the potential of a new morph is not merely producing new offspring—it is charting an entirely new genetic landscape. This journey is challenging, uncertain, and often solitary.

In the realm of polygenic traits, where multiple genetic factors must align for the correct phenotype to appear, it is nearly impossible for one person to find all the answers alone.This is why shared data, collaborative discussion, and mutual respect among breeders are more important than ever.

WithGecko has been at the forefront of creating this environment, and I believe their efforts are pushing crested gecko genetic understanding forward in meaningful ways.

I sincerely hope that Marbling will one day be recognized universally as a distinct morph—and that when that day comes, WithGecko’s name will stand proudly at the center of its history.

The more there is left to uncover, the greater the potential ahead.And to the one walking this path ahead of the rest, WithGecko, I offer my deepest respect and support.

May every ongoing study, honest doubt, unexpected discovery, and shared experience bring us all one step closer to the truth of Marbling.Once again, I extend my heartfelt gratitude to WithGecko for their time, openness, and willingness to share.

I look forward to the bright future of Marbling.