Warts are an opportunistic infection, meaning they are everywhere, they just need the right combination of environments to affect a person.  Very often they are transmitted in areas where you may go barefoot, such as a locker room or shower or gym floor, and once the wart virus enters the bottom of the foot, it thrives.  It just needs a chance to get into the skin, such as a small cut or scrape.  The tendency to be susceptible to warts also runs in the family.  It may be that the pH of one family members' feet or the condition of the immune system of another family member may be slightly different, which leaves them more vulnerable than others.  Either way, if you are concerned about a wart possibly infecting your foot, make an appointment to have your foot evaluated by one of our doctors.