I am 13. Me and my dad both are not numbed by lidocaine- in nasal spray, jelly, or dental injections- and we have no idea why

From http://en.wikipedia.org/wiki/Lidocaine :

"Insensitivity to lidocaine"

Relative insensitivity to lidocaine is genetic. In hypokalemic sensory overstimulation (http://en.wikipedia.org/wiki/Hypokalemic_sensory_overstimulation), relative insensitivity to lidocaine has been described in people who also have attention deficit hyperactivity disorder. In dental anesthesia, a relative insensitivity to lidocaine can occur for anatomical reasons due to unexpected positions of nerves. Some people with Ehlers-Danlos syndrome are insensitive to lidocaine.