Do you ever give your DC coffee as a treat?
Sat in a coffee shop with SIL and the people on the next table have bought their 3 DC (aged between 7-12ish) a coffee each. SIL commented that she’d never pay Starbucks prices for her son(11) to have a coffee, but she does let him have one at home when he’s feeling a bit tired or as a treat when he’s done his homework 
DD is only 3 and hasn’t asked for coffee yet, but I’m almost certain I wouldn’t let her have one.