Dr. Bert Vogelstein and his partners study the causes of cancer. In 2017, they published a study of 32 types of cancer. The study concluded that most cancer cases are caused by DNA replication errors. In fact, 66% of the cancer cases they studied were caused by random DNA replication errors. Environmental factors such as diet, sunburns, and smoking caused 29% of the cancers. The last 5% of cancers in the study were caused by inherited factors. Other researchers study the effects of small changes in the DNA sequence. These small changes trigger changes to genes. Genes that differ by a single nitrogen base are called SNPs (pronounced “snips”). SNPs cause many different disorders. What is true of all genes? A. They use the same kinds of tRNA during protein synthesis. B. They have the same DNA sequence. C. They have the same mRNA sequence. D. They code for proteins with the same amino acid sequence.