I'm of the same opinion. At first, when I was purchasing trios for future breeding projects, I was thinking I would ID the males ASAP and slow their growth to time the maturity to coincide with the female's (assuming I got atleast 1.1). As I've been waiting for them to grow up and as I'm evaluating how the hobby is starting to get legally constricted and the outlook over the next decade, I've come to the realization that for some species, the bloodlines we have may become the only ones we'll ever have in the hobby. It's incredibly short sighted to bottleneck the genetics now when they are more widely available. My new strategy is purchase a trio, raise them up, loan or sell the males, and keep the females. When the females get to say 65% adult max size, invest in another trio for the species. Raise those up, keep the males, and sell/trade any females (keeping two, one from each bloodline preferably). It stretches projects over a longer time frame and requires more startup capital, but I see it as the more responsible path for the longterm preservation of the species in the hobby.
...not to mention the hybridezation that happens by those accidentally pairing brocklehurstis to genics, bud. But yeah, don't inbreed if it can be avoided.
Sadly definitely not a one off. It's very common. As stated the effects are not known though.
Yeah the hybridization in a family of animals that is already very poorly understood or studied really pisses me off. Like let's throw more wood on a dumpster fire.
I've seen quite some brocklehurstis lately labeled as genics the past couple years. Hence I only buy from reputable sources, which of course, makes it difficult for newer breeders to establish themself, but that's just how it goes. The problem is some (probably the minority) doesn't do their research and listen only to what others say - and that may not be correct either. In this hobby always double-check to be on the safe side especially when it comes to breeding.
Hobby "brocklehursti" are geniculata as far as I'm aware, the real A. brocklehursti is a junior synonym of A. theraphosoides and is easily distinguishable from A. geniculata.
I would avoid inbreeding as far as possible, that means you shouldn't knowingly mate siblings. I have no evidence for the following statement, but there is some logic behind it:
well yeah this would apply to their siblings, not their mom.
Ask the dealers about any information they are willing to share. Try to get different sizes at the same time, raise up some then purchase slings again from another dealer (you may get half siblings this way, but its better than sibling to sibling or mother to offspring inbreeding) or if you know yours was CB stateside, try to get different sized specimens from a dealer that imports. There are no guaranteed methods, but some strategy is better than no strategy at all.
The point is it implies that close relative inbreeding is undesirable in tarantulas, perhaps unsurprisingly.
I'm aware of that.
How do you tell them apart?
I will refer you to this thread CLICKY in terms of geniculata/brocklehursti thematic. José explained it nicely in post #27 of that thread (@Exoskeleton Invertebrates)