Scientists know that certain genes are linked to psoriasis. So, if someone in your family has the condition, you may have the same genes and be more likely to get it yourself. Even when people have the right mix of genes, however, they also need something that triggers, or wakes up, their disease. It could be something physical, like a cut, scratch, bad sunburn, or an infection like strep throat. Stress, some medications, and cold weather (which can cause dry, cracked skin) are also common triggers.