Coffee has a total of 23 NMT genes, which arose primarily via a series of gene duplication events. The collection of duplicated genes is distinct from the ones found in tea and cacao, two other caffeine-producing plants that are more closely related to each other. That suggests that these two lineages evolved the ability to give humans a jolt separately.
Coffee’s NMTs also exhibited evidence of positive evolutionary selection, indicating that caffeine biosynthesis may serve an adaptive purpose only in coffee. The function of its convergent evolution in the other drinks was not explored.
Obviously God, nature, the Universe or somebody wants us to be happy in the morning.
The science is settled, so go on and have another cup.