I have never seen any studies that support her conclusions, so I would have to assume that she is basing her "opinion" on anecdotal evidence. This is either what she has heard from others, or it comes from her own interaction with snakes.
If it is the latter, I can imagine why it is that females tend to be more aggressive in her experiences. When a male is brought to a vet, it is usually because it is not eating properly, and the owner had done all that can be down without access to prescription drugs or complicated procedures. Snakes (of either sex) brought to a vet in this state are usually near death, and are all very docile, not having the energy to do much of anything often times. However, females are brought to the vet for egg binding and other procedures that, while serious, often times do not leave the animal as listless as other situations. So, in the analysis of snakes taken to vets, I would imagine that females are statisically more likely to be aggressive when handled by a vet. But, the "n" of that analysis, the population to be analyzed, is skewed, as we can all see.
For myself, I have had two corns that were just terrible! Biting every time and musking all over the place, regardless of how frequently they were handled or for what duration the handling was. One was a male lavender that I sold last year to another breeder, and the other is a hypo female het for bloodred that I still have. Nasty little things, they were, and she still is the meanest thing I've ever seen! LOL
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Darin Chappell
Hillbilly Herps
PO Box 254
Rogersville, MO 65742