Should I tell my parents what to wear?

Did anyone have strong feelings about what their parents should/should not wear to the wedding? We are getting married at my aunt’s house, so it’s not too fancy, and as of right now I have told my dad to wear a grey suit (like to groomsmen) and have told my mom she can wear whatever she feels comfortable in. For people that didn’t specify, do you regret not giving some guidance? For future brides, what are your thoughts on parent’s attire?