The gift that keeps on giving.
well, if you exclude Islam, then quite often diversity is very, very good.
Take the English - prior to the 1790s they were already a mix of Celtic Britons + Romans + Celtic Irish, Scots, Welsh and Cornish mixed with Angles, Saxons, Jutes and then Danes and toss in the Normans and then French Huguenots, then Jews
From 1790 they merged in various Germanic peoples, then Eastern Europeans, Italians etc.
Or the USA — a very successful mixed nation.
Or the French - Germanic, Celtics, Romans etc.
It’s Islam that is the fly in the ointment