The botanical definition of a “nut” is a fruit whose ovary wall becomes very hard at maturity. Using this criterion, the peanut is not a true nut, but rather a legume. However, for culinary purposes and in common English language usage, peanuts are usually referred to as nuts, according to Wikipedia.
When I wear this shirt, people come up to me. It is one of those shirts that encourages discussion. And why do I suspect that that nut touching happens more often in San Francisco when compared to other towns with more than 864,000 inhabitants.
It turns out that peanuts, along with beans and peas, belong to the single plant family, Leguminosae. Legumes are edible seeds enclosed in pods. (www.peanut-institute.org/peanut-facts/)