Suppose I want to start an AltCoin, and set it up for merged mining with Bitcoin. Will it require the AltCoin clients to also download the Bitcoin blockchain to verify the hashes embedded in the blocks, or do only the miners need a copy of both chains?

Suppose I want to start an AltCoin, and set it up for merged mining with Bitcoin. Will it require the AltCoin end-users to also download the Bitcoin blockchain to verify the hashes embedded in the blocks, or do only the miners need a copy of both chains?