Just to be clear, spiders are not the only morphs to wobble. See http://www.owalreptiles.com/issues.php (thank you mr owal). Any time one parent has the spider gene you have a 50% chance of the offspring being spider. And once again, the severity of the displayed wobble seems to have more to do with stress than anything else. Severe wobble can be reduced to minor one and a minor wobble can be increased to a severe one all in the same snake with the right triggers.