The 2 Albrecht brothers inherited a single grocery store from their mother in 1945. They split the business for no obvious reason, a tobacco dispute might have stood in the background and they decided to separate a little before getting into serious trouble with each other. They never competed each other and the businesses still co-operate.

They drew a line through their home town and divided Germany north and south... so when will Germany ever be really united (fun)?

When they expanded, they went country by country. USA is Aldi South.

Both brothers, Karl and Theo, worked in their business until very old age and never appeared in public. Currently, the "North" owning family branch is in a dispute. Old Theo would have hated it.

Lidl is a competitor of both Aldi operations with an almost identical concept: Mostly own brands, simple but functional shops, good internal quality control, reliably customer oriented.