Brown, who won a 2010 special election to succeed the late Democratic Sen. Edward Kennedy, has called onWarren to release her personnel records. Warren again declined on Monday, saying her background had no impact on her hiring.
Charles Fried, a member of the committee that reviewed Warren for the Harvard post, has said the question of her ancestry was never mentioned.
Democrats, in turn, faulted Brown on Monday for failing to identify the employers or occupations of a higher percentage of big money donors than Warren.
According to Federal Election Commission reports, more than 16 percent of donors to Brown's campaign did not identify where they worked or what they did for a living. The donors accounted for $2.1 million of the $13.1 million Brown collected in donations over $200.
That compares with less than 2 percent for Warren. Those donors accounted for about $248,000 of the more than $16 million Warren collected in donations over $200. Campaigns do not have to give itemized lists of donors who give less than $200.
The story was first reported by the Patriot Ledger.
Brown's campaign said it has followed all FEC requirements, including sending letters to those donors asking them for information about their employers and occupations.
"Scott Brown is in full compliance with all rules and regulations," said Brown campaign manager Jim Barnett, noting that other elected officials including President Barack Obama have similar rates of compliance.