Warts occur when the virus comes in contact with your skin and causes an infection. Warts are more likely to develop on broken skin, such as picked hangnails or areas nicked by shaving, because the virus is able to enter the top layer of skin through scratches or cuts. While dermatologists still don’t know why, certain people are more likely to get warts than others. Additionally, children get warts much more often than adults, because their immune systems have not yet built up their defenses against the numerous types of human papillomavirus that exist.