Breed a Twin in Dragonvale – What are the chances?

The Cooperative Breeding Cave (CBC) was added to the Dragonvale in its 4th year, as a way of allowing some interaction between players. You can breed one of your dragons with the dragon of a friend. This can give you access to dragons you don’t have, for cloning purposes, and/or to use in specific breeding combinations. It also gives you a new type of dragon to collect …

Twins

“Sometimes Cooperative Breeding can result in twins, one for each participating player. Twins are special dragons that have unique heraldry to celebrate their special nature.”

Twin dragons look identical to their non-Twin counterparts, but they have a blue orb above their head (from level 1) and Twin pedestals have a blue glow. They are a separate set of dragons to collect, that are tracked by the game. But this post is primarily an examination of the first word in the Twins description …

“Sometimes …”

To jump a head a little to the data collection part of the post, at the time of writing, I have a record of 2003 breeds in the CBC, and they have resulted in 209 Twins. The overall percentage chance is 10.43%, or ~1 breed in every 10. I think most long term players will say that seems about right, so I’m going to start with an assumption of 10% chance of breeding a Twin.

Back to Back Twins

If there was just a flat 10% chance of breeding a Twin, then the chances of getting a Twin immediately after you bred one, would be 10%. You would breed 2 twins in a row, 1 time in 10. But I have almost never bred back to back Twins in my many years of playing the game.

The chances of breeding a Twin on the 2nd breed after breeding a Twin, would be 10% of the remaining 90% (10% being used up on the 1st breed) which would be 9%. Or 19% chance of breeding a Twin on the first 2 tries breed after you just bred one. Roughly 1 in 5. Again, this is also not my experience in the game.

The chances of breeding a Twin on the 3rd try would be 10% of the remaining 81%, or 8.1%. Etc. The graph of a set 10% chance of breeding Twins, looks like this.

But as we have said, this does not seem like the Dragonvale experience.

Axew

This thought occurred to Axew, a player who posts at the Dragonvale discord. They decided to collect the data, to have a more concrete answer. After nearly 1000 breeds and 98 Twins, they graphed the data. I reproduce it here, with permission.

Their experience implies that you very rarely get a Twin in the first 4 breeds. The most likely breed of a Twin occurs on the 5th, and the odds gradually decrease from there. They had a total of 4 Twins over the first 4 breeds, and then 15 Twins on the 5th. A reasonable guess is that you have a 1% chance of breeding a Twin on breeds 1 to 4, and then 15% on breeds 5 and onwards.

Percentage Chance

I put their data into a table along with the percentages. It contains an expected percentage column based on 4 lots of 1%, and then 15% thereafter. I added conditional formatting to show if the actual results are within 5% (higher or lower) of the expected (green), or outside that (red). This will serve as a visual indicator of our supposition matching reality, although 98 is a small sample size.

None of the individual breed numbers are within the +/-5% window. This is not surprising, because of the small sample size, and how small the variation is. On the 1% chance of breeding a Twin on the first try, the variation is from 0.95% to 1.05%. And even on the biggest chance, of 14.41% on the 5th breed, the window is from 13.69% to 15.13%. With such small numbers, it was unlikely this small sample size would match. We need a much larger data set, and more on that below.

However the cumulative numbers show some correlation. 4 breeds in the first 4 attempts is what we expect if they each have 1% chance. 5th breed is slightly higher than expected at 19.39% (19.27% is the cut off), but 6, 7 & 8 are within the margin of error. That suggests we might be correct with our percentages from 1 to 8.

From there the actual numbers are higher than the expected, right up to breed 19, where we hit 100%, though our initial guess predicted a 91% chance. That percentage is probably off, because 91% means, 1 time in 12, it would take more than 19 breeds. The game might have another boost at the higher breed numbers, to get close to 100% at approx 20 breeds. Or perhaps, 19 is the maximum allowed, and you are guaranteed a Twin if you haven’t gotten one in the first 18 breeds. Speculation on that in another post.

Why is this Important?

It means that the first 4 breeds at the CBC are very rarely going to get you a Twin. And if you are trying for a Twin of a specific dragon, you should speed past the first 4 breeds as quick as you can. Those first 4 breeds could be 10 hours or longer, taking up 2 days of breeding, or costing you 40+ gems to speed up. Worse than that, you might actually breed the dragon you’re trying for, whilst almost guaranteeing that it won’t be a Twin.

Skip the First 4 Breeds with Plant + Plant

Axew (and Quil and I) recommend skipping past those first 4 breeds as quick as you can, and the data backs this up. The easiest way to do that is to breed your Plant dragon with another players Plant dragon. And in 30 seconds you’ll be on to the 5th breed, and your chances of a Twin have gone from 1% to 15%. With that in mind, I have created a park, to permanently share a Plant dragon.

Send a friend request to _Twin_#7878

and message me to add you. (Email me, or reply to this post.) Then a Plant dragon will always be ready to go, and very close to the top of your friends list. This is not a park being used, so please don’t send gems or treats. It is just there as a service for you.

Collecting Data

I’m also going to be collecting Twins data going forward. I have bred 100+ Twins myself, to add it to the pool of results. The goal is to get as close as we can to the correct percentages. If you are keeping a track of your Twin breeding now, or in the future, please send me your results, or post in this thread at the Dragonvale Community Forum. All the collected data will be added to this spreadsheet/graph, HERE.

Thanks to Axew, for starting the conversation, and Quil, for sharing it with me.

All my Dragonvale posts are Indexed HERE for easy access.