Different Plants, Same Parentage?

I’m very new, please forgive if this is Day 1 stuff. I assumed that if you use plant A as the pollen parent and plant B as the seed parent, you will get plant AB every time. And you’d get plant BA every time you do the reverse. But I just paid for premium access on Helpmefind.com and found 3 plants with the exact same parentage: MAClocker, SUNambro, and MACmiskiz. I was hoping to recreate MACmiskiz, but now I’m confused. Someone please explain!

Much like with people, two parents generally have very different children. They may produce similar children but two children getting the same chromosomes is something like 1 in 6.27billion.

Most modern roses tend to be tetraploid (4 sets of 7 chromosomes). Each seedling will only get half from each parent, which half will be different for every seedling.

Welcome, Liz! Combining the same two parents will virtually never recreate the same rose. It MAY create similar ones, or it may not. As Plazbo explained, it all depends upon the genetics of the roses involved. It is very common for a breeder to find a combination which produces roses good enough for introduction. Once you’ve really studied the breeding of commercial roses, you will find MANY which share the same parents from the same breeder. Each seems to have had her or his favorite combination so they keep going back to that same cross to see what else they might mine from it. In the example you cited, the parents had fairly homogeneous backgrounds. Imagine mixing it up a bit and making one of them have a very mixed background, perhaps something containing climbing types or even miniatures. The results of repeated crossings of those mates may result in miniature bushes, miniature climbers, full sized bushes and full sized climbers. If the climber used was once-flowering, you may even have offspring which flower only in spring, or perhaps spring and fall or even continuously. You can recreate the cross which produced a rose you find intriguing, but you won’t “recreate” the intriguing rose. You may get close, but you won’t ever recreate it exactly. I remember reading in the 1990’s that only twice had modern roses been determined to have been sufficiently “identical” to be deemed the same rose. They were roses from differing crosses made by different people. They resembled each other so closely, the industry made them synonymous. Twice out of how many hundreds of thousands of introduced types. Not to mention the likely millions of seedlings which didn’t make the cut for introduction. Thank goodness you can’t just mix it up and make a new one of the same, like following a recipe for baked goods! That would take all the fun and serendipity out of it!

Welcome, Liz!
When you buy a named cultivar of rose, you are generally purchasing a clone that was asexually created to be identical to the named plant/cultivar from which e.g. a cutting might have been taken and rooted, or more commonly grafted.

When you grow plants from seed on the other hand (sexual reproduction) the analogy of siblings works well. Pure species roses tend to have lots of similarities, and might appear identical to our eye, but when more complex crosses are mixed with a wide-reaching diversity of genetics, they can be widely different with, for instance, different colors and petal counts, and some being climbers while some might be miniatures… All despite being siblings. (A litter of wolf pups, for instance, might look relatively similar, whereas sibling mutts descended from purebreeds can reveal a bit more diversity.)

When you buy a rose from a modern, complicated cross, only the best of the best will have survived the selection process to become named and marketed cultivars. If you recreate a cross, it will not be identical, and in fact, maybe about 1/1000 of seedlings from the same cross might not even be deemed to be marketable. (The vast majority of seedlings from planned crosses typically will be deemed inferior.)

Using the human genetics analogy, as hybridizers our goal might for instance be to cross a Mike Tyson with an Albert Einstein (which in theory would be possible since most rose flowers can be used both as male and female, and rose cultivars are passed on for many generations) with the intention of creating an incredibly brilliant athlete. The odds of the stars aligning to create somebody as smart and as athletic as the selected parents are not in your favor, as you might imagine.

Fortunately, one can create thousands of seedling and cull the inferior ones much more ethically than one could with humans!

There are many examples of “siblings” created and surviving the selection process to be introduced in rose hybridizing. Famously, if you look up Mister Lincoln, Papa Meilland, and Oklahoma, you will find all three roses were independently bred (with similar goals) around the same time from the same two celebrated red rose parents in hopes of combining the best features of each. They are similar, as were their parents, but they are distinctly different.

Hope that makes sense and helps.

This one is more simple than it seems

Two of those are from the same breeder, McGredy, who produced both parents as well. Both of those parents were commercial successes and very common parents in his breeding lines moving forward. I am sure he produced many more seedlings from the same parents.

The other breeder lives in the same small country island, New Zealand. NZ has what NZ offers, what they can get from Australia, and rarely what they can get elsewhere. So you can see possibilities tend to shrink in such circumstances. So the likelihood is higher since that breeder is near the other breeder, and both of the parents were highly successful commercially (as far as roses go at the time).