Common sense is the collection of prejudices acquired by age eighteen.

Albert Einstein (1879-1955) German-American physicist

(Spurious)

Not found in Einstein's writings. There is no evidence of Einstein saying or writing anything like this. It's deemed probably not an Einstein quotation by Einstein scholar Alice Calaprice, The Expanded Quotable Einstein (2000).

Variants:

As Einstein has pointed out, common sense is actually nothing more than a deposit of prejudices laid down in the mind prior to the age of eighteen.
[Lincoln Barnett, "The Universe and Dr. Einstein, Part 2," Harper's Magazine (May 1948), reprinted in The Universe and Dr. Einstein (1950); Einstein wrote the foreword to the book.]

Common sense is that layer of prejudices which we acquire before we are sixteen.
[E. T. Bell, Mathematics, Queen and Servant of the Sciences (1951)]

More discussion of this quotation: Common Sense Is Nothing More Than a Deposit of Prejudices Laid Down in the Mind Before Age Eighteen – Quote Investigator.