321 Coffee employs people with developmental disabilities throughout the Triangle. Like many other firms, 321 Coffee is celebrating inclusivity Thursday for World Down Syndrome Day. People with Down syndrome have three copies of their 21st chromosome, which is why the 21st is the day the community celebrates. And one typical tactic is wearing brightly colored mismatched socks, as chromosomes are shaped like socks. 321 Coffee is planning a big corporate event Thursday morning at Pendo's headquarters as well as weekend community events at its shops in Raleigh and Durham.