The children were on their best behavior during the wedding, with the help of Kate, who gave them a gentle "shhh" signal from Kate as they entered the church, HELLO
You could wear your favorite pair of jeans/shorts, some jeans that have a design embroidered on them, jeans that have patches, ripped jeans, or jeans that have two different washes on them
The all-too-familiar Business Casual Collared shirt (and/or nice sweater) Chinos, khakis, or wool pants (never shorts) Decent shoes (not sneakers) Decent jacket This is similar to smart casual and may be in the same category to some people
In traditional households, mothers are the ones who choose and buy clothing for the children, so this is your chance to provide input as a gentleman of style