As far as BREEDING anything goes (plant wise) these days ,it takes several seasons in isolation (8 minimum) to see what you have as far as stability goes.
8 seasons is IF it grew stable and needed no back crossing etc.
Breeding takes a LOT of work.

These days you are lucky to get an F4 or F5 generation of especially super hots sold as a new strain or variety.

I grew a 7 pot that was from CARDI in isolation for 4-5 seasons in isolation before it reverted back to it's roots.

The seeds were pure and the variety,to this day is considered stable by many who sell the seeds.
Nobody grows stuff in isolation for seeds in their garden anymore.
Most new stuff is forgotten soon as something else is [popular.
A lot of stuff called new strains or crosses these days are far from stable.

Grafts are a different story,it depends on what gets grafted to what as to what the end result will be.
Grafts don't grow stable seeds even though a particulare grafted plant had certain specifics.

I do see cuttings from unstable crosses as being the only way to get whatever the unstable cross or whatever produced.
Too much $ in seeds to depend on what is stable and what isn't.
IF a vendor advertises anything as the next hottest,people will buy it even if it isn't or is so unstable that 1 in 10000000 grows somewhat true.
By the time you figure out you got bunk seeds there is a new so called Strain or cross that is the latest thing.
People forget about the last rip off they purchased.
They just buy the new latest thing...

Breeding is getting to be a lost art.
With genetic engineering they don't have to breed or develope hybrids.
They play with genes to get what they want as an end product these days.
Then you have the GMO stuff that a lot of times has genes from unrelated stuff in it for one reson or another.

Genetic engineering is almost all traditional hybridization work once you get past the "in the lab" stuff, fwiw.

Once you get your gene into the plant it's pretty much traditional breeding. You're trying to sexually pass on the desired traits (and whatever genes you've already stabilized and bred into past plants) into new plants.

Very rarely does any genetic engineering start from scratch...you've got traits you've already developed and stabilized in other plants and you're trying to introduce new traits (usually one at a time) into your new genetically engineered crop...whether it be a new trait or an improved trait. It's just like traditional hybridization breeding in this aspect. This is how trait stacking happens. It's not all done at once from scratch. There's breeding stock that already contains traits you desire that can predictably be passed on.

The real "hands in the lab" part of genetic engineering is breaking apart DNA, inserting the desired trait, and reassembling it...then inserting it into a new delivery package (usually a virus or bacteria containing modified bacterial DNA containing your desired trait) which is "shot" into the target plant (which is now a breeding candidate).

The rest of it is pretty much traditional hybrid breeding and seeing what sticks...with an extremely high failure rate (we're talking 99%+ until you find a solid/stable hybrid).

You get it into the plant...replications of the DNA "infect" the plant with the new DNA, but instead of getting sick, it gets a trait not present in that plant...when the plant is bred with another plant and if it's sexually passed on, the hybrid seed can express this trait. It's a "finished" product when the new trait is mixed with the stack of old traits you've bred from the other plant and everything desired expresses itself as desired.

...then it comes down to looking at it back in the lab to make sure it's expressing itself correctly on the genetic level and all kinds of other quality control...but we're back in the lab crosschecking and looking at the results rather than "making" anything happen at this point.

The problem I see with genetic engeneering is they put genes in stuff that would never happen in nature.

If they just used it as a shortcut for any given species I wouldn't have a problem with it.
Swap different Pepper genes between each other to fast track hybrids etc.

But putting stuff,even non plant related into a plant opens the door to making possible franken plants.

For instance lets say they used a gene from an invasive plant into wheat and suddenly Wheat could cross pollinate with a plant it couldn't in nature by itself.

Lets say the invasive genes became dominant in F2 etc. crops.
So it's possible that you get a new weed crop and add to that the roundup ready stuff.
Pandora's Box?
They release some of this stuff in countries with little or no regulations for testing.
A lot of this stuff ends up sucking big time.

I think there needs to be more oversight as to what the gene swapping can produce in the long run.

I see GMO stuff as being a possible good thing BUT there isn't enough regulation right now as to long term use of the GMO plants.

Also,Lab grown stuff takes a lot less time to produce the desired traits.
Cross breeding in a garden would take a lot more time.

Like the old commercial said"You shouldn't mess with Mother Nature".