Are arachnophobics more subceptible to toxical effects coming from spider toxins?
This is an interesting question and may stem from the fact that spider phobias tend to run in families and thus have a genetic link - assuming susceptibility to toxin levels can be passed from parent to offspring. However, instead a study found that the fear of spiders was caused by social learning of disgust reactions.
Directly from source:
In relation to the first question, it has been known for many years that spider phobia tends to run in families. It has often been assumed that this may represent a biological predisposition caused by the transmission of genes between parents and offspring. However, we found that this relationship was considerably more complex and indirect. We found that the only significant predictor of a child’s spider fear was not the level of spider fear in the parents, but their levels of disgust sensitivity. One interpretation of this finding is that spider fear may be transmitted within families as the result of social learning of the nature and intensity of disgust reactions–including disgust reactions to spiders.
Link to study abstract: http://www.sciencedirect.com/science/article/pii/000579679390041R