Configurable Cascade of Email Owner from Account

Hi- we've been reassigning accounts in CRM and the change of ownership appears to be cascading down to emails.  That is, the owner of the email records associated with an account is changing whenever we change the owner of the account.  How I can prevent this from occurring?  I'm looking at the N:1 relationship between Account and Email and not seeing the Owner field as something that's getting changing.  See picture.  Am I missing something?

Thanks!