Actually, I don't know.. I have thayeri and I also have graybands. In fact I also have an alterna X thayeri line that I like their own merits.(I did not originate the cross but breed them true to each other)
I do not cross any of my snakes since I once put a thayeri in with a mex-mex. It wasn't on purpose but I got distracted. All of the babies from that breeding are accounted for and each person who got one was told exactly what they were.
Anyway, I know quite a few breeders and some do have hybrids and some don't. Those who do have them tend to be very straightforward about the lines and they are usually not the problem.
It is when the snakes change hands a few times that there could be problems down the road I guess.
In my opinion and for what that's worth, you should talk to each person you buy from directly if possible.
I get much more than just the lineage of the snakes in question as I learn about the breeder himself. I can get the feel of the direction he may be taking ($$ vs. hobby, etc)
You know, you can tell in most cases if someone is honest and straight with you and whether or not he knows what he's doing.
When I run into someone who cannot tell honestly what I'm looking at (snake) then I usually decline to offer up my $$.
There are of course those who really don't know what they have and I suspect many of us fall into that gray area once in a while as we're just going on what we were told when we acquired the parents or whatever. So you see, honesty is the biggest deal here. Whether or not you know what the heck you have or not, just be truthful and let others decide.
Sooner or later if we are not on the up and up, legislation will creep into the hobby and bring it to its knees.
:Mark
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Surrender Dorothy!
www.crimsonking.funtigo.com